diff --git a/src/Microsoft.OData.Edm/Csdl/Parsing/Ast/CsdlPropertyReference.cs b/src/Microsoft.OData.Edm/Csdl/Parsing/Ast/CsdlPropertyReference.cs
index 23fa24dca9..faa23393ba 100644
--- a/src/Microsoft.OData.Edm/Csdl/Parsing/Ast/CsdlPropertyReference.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Parsing/Ast/CsdlPropertyReference.cs
@@ -11,17 +11,15 @@ namespace Microsoft.OData.Edm.Csdl.Parsing.Ast
     /// </summary>
     internal class CsdlPropertyReference : CsdlElement
     {
-        private readonly string propertyName;
-
-        public CsdlPropertyReference(string propertyName, CsdlLocation location)
+        public CsdlPropertyReference(string propertyName, string propertyAlias, CsdlLocation location)
             : base(location)
         {
-            this.propertyName = propertyName;
+            PropertyName = propertyName;
+            PropertyAlias = propertyAlias;
         }
 
-        public string PropertyName
-        {
-            get { return this.propertyName; }
-        }
+        public string PropertyName { get; }
+
+        public string PropertyAlias { get; }
     }
 }
diff --git a/src/Microsoft.OData.Edm/Csdl/Parsing/CsdlDocumentParser.cs b/src/Microsoft.OData.Edm/Csdl/Parsing/CsdlDocumentParser.cs
index d52d0d9a7f..2b09018daf 100644
--- a/src/Microsoft.OData.Edm/Csdl/Parsing/CsdlDocumentParser.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Parsing/CsdlDocumentParser.cs
@@ -364,7 +364,7 @@ private static CsdlKey OnEntityKeyElement(XmlElementInfo element, XmlElementValu
 
         private CsdlPropertyReference OnPropertyRefElement(XmlElementInfo element, XmlElementValueCollection childValues)
         {
-            return new CsdlPropertyReference(Required(CsdlConstants.Attribute_Name), element.Location);
+            return new CsdlPropertyReference(Required(CsdlConstants.Attribute_Name), Optional(CsdlConstants.Attribute_Alias), element.Location);
         }
 
         private CsdlEnumType OnEnumTypeElement(XmlElementInfo element, XmlElementValueCollection childValues)
diff --git a/src/Microsoft.OData.Edm/Csdl/Parsing/SchemaJsonParser.cs b/src/Microsoft.OData.Edm/Csdl/Parsing/SchemaJsonParser.cs
index b9575d8dd9..42c47be17c 100644
--- a/src/Microsoft.OData.Edm/Csdl/Parsing/SchemaJsonParser.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Parsing/SchemaJsonParser.cs
@@ -653,19 +653,36 @@ internal static CsdlKey ParseCsdlKey(string name, JsonElement keyArray, JsonPars
 
             IList<CsdlPropertyReference> properties = keyArray.ParseAsArray(context, (v, p) =>
             {
+                string alias = null;
+                string propertyName = null;
                 if (v.ValueKind == JsonValueKind.Object)
                 {
-                    // TODO: ODL doesn't support the key referencing a property of a complex type as below.
+                    // Key properties with a key alias are represented as objects with one member
+                    // whose name is the key alias and whose value is a string containing the path to the property.
                     // "$Key": [
                     //    {
                     //      "EntityInfoID": "Info/ID"
                     //    }
                     //  ]
-                    p.ReportError(EdmErrorCode.InvalidKeyValue, "It doesn't support the key object.");
+                    var objectProperties = v.EnumerateObject();
+                    if (objectProperties.Count() != 1)
+                    {
+                        p.ReportError(EdmErrorCode.InvalidKeyValue, "Key properties with a key alias are represented as objects with only one member.");
+                    }
+                    else
+                    {
+                        var property = objectProperties.First();
+                        alias = property.Name;
+                        propertyName = property.Value.ParseAsString(context);
+                    }
+                }
+                else
+                {
+                    // Key properties without a key alias are represented as strings containing the property name.
+                    propertyName = v.ParseAsString(context);
                 }
 
-                string propertyName = v.ParseAsString(context);
-                return new CsdlPropertyReference(propertyName, context.Location());
+                return new CsdlPropertyReference(propertyName, alias, context.Location());
             });
 
             return new CsdlKey(properties, context.Location());
diff --git a/src/Microsoft.OData.Edm/Csdl/Semantics/BadElements/UnresolvedPropertyRef.cs b/src/Microsoft.OData.Edm/Csdl/Semantics/BadElements/UnresolvedPropertyRef.cs
new file mode 100644
index 0000000000..d3e9c8906a
--- /dev/null
+++ b/src/Microsoft.OData.Edm/Csdl/Semantics/BadElements/UnresolvedPropertyRef.cs
@@ -0,0 +1,28 @@
+//---------------------------------------------------------------------
+// <copyright file="UnresolvedPropertyRef.cs" company="Microsoft">
+//      Copyright (C) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+// </copyright>
+//---------------------------------------------------------------------
+
+using Microsoft.OData.Edm.Validation;
+
+namespace Microsoft.OData.Edm.Csdl.CsdlSemantics
+{
+    internal class UnresolvedPropertyRef : BadElement, IUnresolvedElement, IEdmPropertyRef
+    {
+        public UnresolvedPropertyRef(IEdmStructuredType declaringType, string name, string alias, EdmLocation location)
+            : base(new EdmError[]
+            {
+                new EdmError(location, EdmErrorCode.BadUnresolvedPropertyRef,
+                    Edm.Strings.Bad_UnresolvedPropertyRef(declaringType.FullTypeName(), name, alias))
+            })
+        {
+        }
+
+        public IEdmStructuralProperty ReferencedProperty => null;
+
+        public string PropertyAlias { get; }
+
+        public string Name { get; }
+    }
+}
diff --git a/src/Microsoft.OData.Edm/Csdl/Semantics/CsdlSemanticsEntityTypeDefinition.cs b/src/Microsoft.OData.Edm/Csdl/Semantics/CsdlSemanticsEntityTypeDefinition.cs
index c362edb1a7..fc222face5 100644
--- a/src/Microsoft.OData.Edm/Csdl/Semantics/CsdlSemanticsEntityTypeDefinition.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Semantics/CsdlSemanticsEntityTypeDefinition.cs
@@ -14,7 +14,7 @@ namespace Microsoft.OData.Edm.Csdl.CsdlSemantics
     /// <summary>
     /// Provides semantics for CsdlEntityType.
     /// </summary>
-    internal class CsdlSemanticsEntityTypeDefinition : CsdlSemanticsStructuredTypeDefinition, IEdmEntityType, IEdmFullNamedElement
+    internal class CsdlSemanticsEntityTypeDefinition : CsdlSemanticsStructuredTypeDefinition, IEdmEntityType, IEdmFullNamedElement, IEdmKeyPropertyRef
     {
         private readonly CsdlEntityType entity;
         private readonly string fullName;
@@ -23,8 +23,8 @@ internal class CsdlSemanticsEntityTypeDefinition : CsdlSemanticsStructuredTypeDe
         private static readonly Func<CsdlSemanticsEntityTypeDefinition, IEdmEntityType> ComputeBaseTypeFunc = (me) => me.ComputeBaseType();
         private static readonly Func<CsdlSemanticsEntityTypeDefinition, IEdmEntityType> OnCycleBaseTypeFunc = (me) => new CyclicEntityType(me.GetCyclicBaseTypeName(me.entity.BaseTypeName), me.Location);
 
-        private readonly Cache<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmStructuralProperty>> declaredKeyCache = new Cache<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmStructuralProperty>>();
-        private static readonly Func<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmStructuralProperty>> ComputeDeclaredKeyFunc = (me) => me.ComputeDeclaredKey();
+        private readonly Cache<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmPropertyRef>> declaredKeyCache = new Cache<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmPropertyRef>>();
+        private static readonly Func<CsdlSemanticsEntityTypeDefinition, IEnumerable<IEdmPropertyRef>> ComputeDeclaredKeyFunc = (me) => me.ComputeDeclaredKey();
 
         public CsdlSemanticsEntityTypeDefinition(CsdlSemanticsSchema context, CsdlEntityType entity)
             : base(context, entity)
@@ -72,6 +72,14 @@ public bool HasStream
         }
 
         public IEnumerable<IEdmStructuralProperty> DeclaredKey
+        {
+            get
+            {
+                return this.DeclaredKeyRef?.Select(x => x.ReferencedProperty);
+            }
+        }
+
+        public IEnumerable<IEdmPropertyRef> DeclaredKeyRef
         {
             get
             {
@@ -79,6 +87,7 @@ public IEnumerable<IEdmStructuralProperty> DeclaredKey
             }
         }
 
+
         protected override CsdlStructuredType MyStructured
         {
             get { return this.entity; }
@@ -105,32 +114,21 @@ private IEdmEntityType ComputeBaseType()
             return null;
         }
 
-        private IEnumerable<IEdmStructuralProperty> ComputeDeclaredKey()
+        private IEnumerable<IEdmPropertyRef> ComputeDeclaredKey()
         {
             if (this.entity.Key != null)
             {
-                List<IEdmStructuralProperty> key = new List<IEdmStructuralProperty>();
+                List<IEdmPropertyRef> key = new List<IEdmPropertyRef>();
                 foreach (CsdlPropertyReference keyProperty in this.entity.Key.Properties)
                 {
-                    IEdmStructuralProperty structuralProperty = this.FindProperty(keyProperty.PropertyName) as IEdmStructuralProperty;
+                    IEdmStructuralProperty structuralProperty = FindKeyProperty(keyProperty.PropertyName);
                     if (structuralProperty != null)
                     {
-                        key.Add(structuralProperty);
+                        key.Add(new EdmPropertyRef(structuralProperty, keyProperty.PropertyName, keyProperty.PropertyAlias));
                     }
                     else
                     {
-                        // If keyProperty is a duplicate, it will come back as non-structural from FindProperty, but it still might be structural
-                        // inside the DeclaredProperties, so try it. If it is not in the DeclaredProperties or it is not structural there,
-                        // then fall back to unresolved.
-                        structuralProperty = this.DeclaredProperties.FirstOrDefault(p => p.Name == keyProperty.PropertyName) as IEdmStructuralProperty;
-                        if (structuralProperty != null)
-                        {
-                            key.Add(structuralProperty);
-                        }
-                        else
-                        {
-                            key.Add(new UnresolvedProperty(this, keyProperty.PropertyName, this.Location));
-                        }
+                        key.Add(new UnresolvedPropertyRef(this, keyProperty.PropertyName, keyProperty.PropertyAlias, this.Location));
                     }
                 }
 
@@ -139,5 +137,73 @@ private IEnumerable<IEdmStructuralProperty> ComputeDeclaredKey()
 
             return null;
         }
+
+        private IEdmStructuralProperty FindKeyProperty(string nameOrPath)
+        {
+            if (string.IsNullOrWhiteSpace(nameOrPath))
+            {
+                return null;
+            }
+
+            string[] segments = nameOrPath.Split('/');
+            if (segments.Length == 1)
+            {
+                return this.FindProperty(nameOrPath) as IEdmStructuralProperty;
+            }
+            else
+            {
+                // OData spec says "The value of Name is a path expression leading to a primitive property."
+                // The segment in a path expression could be single value property name, collection value property name, type cast, ...
+                // However, for the key property reference path expression:
+                // 1) Collection value property name segment is invalid, right?
+                // 2) Type cast? reference a key on the sub type? it's valid but....
+                // So far, let's skip those.
+                IEdmStructuredType edmStructuredType = this;
+                for (int i = 0; i < segments.Length; ++i)
+                {
+                    if (edmStructuredType == null)
+                    {
+                        return null;
+                    }
+
+                    string segment = segments[i];
+
+                    if (segment.Contains("."))
+                    {
+                        // a type cast, let's skip it.
+                        continue;
+                    }
+
+                    IEdmProperty edmProperty = FindPropertyOnType(edmStructuredType, segment);
+                    if (i == segment.Length - 1)
+                    {
+                        return edmProperty as IEdmStructuralProperty;
+                    }
+                    else if (edmProperty != null)
+                    {
+                        // If the property is a collection value, let's move on using the element type of this collection
+                        edmStructuredType = edmProperty.Type.ToStructuredType();
+                    }
+                    else
+                    {
+                        return null;
+                    }
+                }
+            }
+
+            return null;
+        }
+
+        private static IEdmProperty FindPropertyOnType(IEdmStructuredType structuredType, string name)
+        {
+            IEdmProperty property = structuredType.FindProperty(name);
+
+            if (property == null)
+            {
+                property = structuredType.DeclaredProperties.FirstOrDefault(p => p.Name == name);
+            }
+
+            return property;
+        }
     }
 }
diff --git a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaJsonWriter.cs b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaJsonWriter.cs
index 5944ae5749..22a61c0da7 100644
--- a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaJsonWriter.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaJsonWriter.cs
@@ -201,15 +201,28 @@ internal override void WriteDeclaredKeyPropertiesElementHeader()
         }
 
         /// <summary>
-        /// Write the Key property
+        /// Write the Key property ref
         /// </summary>
-        /// <param name="property"></param>
-        internal override void WritePropertyRefElement(IEdmStructuralProperty property)
+        /// <param name="propertyRef">The property ref.</param>
+        internal override void WritePropertyRefElement(IEdmPropertyRef propertyRef)
         {
-            // Key properties without a key alias are represented as strings containing the property name.
-            // Key properties with a key alias are represented as objects with one member whose name is the key alias and whose value is a string containing the path to the property.
-            // TODO: It seems the second one is not supported.
-            this.jsonWriter.WriteStringValue(property.Name);
+            if (propertyRef.PropertyAlias != null)
+            {
+                // Key properties with a key alias are represented as objects with one member
+                // whose name is the key alias and whose value is a string containing the path to the property.
+                this.jsonWriter.WriteStartObject();
+
+                this.jsonWriter.WritePropertyName(propertyRef.PropertyAlias);
+
+                this.jsonWriter.WriteStringValue(propertyRef.Name);
+
+                this.jsonWriter.WriteEndObject();
+            }
+            else
+            {
+                // Key properties without a key alias are represented as strings containing the property name.
+                this.jsonWriter.WriteStringValue(propertyRef.Name);
+            }
         }
 
         /// <summary>
diff --git a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaWriter.cs b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaWriter.cs
index a299e6a77e..89d6d9ba23 100644
--- a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaWriter.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaWriter.cs
@@ -70,7 +70,7 @@ internal EdmModelCsdlSchemaWriter(IEdmModel model, Version edmVersion)
 
         internal abstract void WriteDeclaredKeyPropertiesElementHeader();
 
-        internal abstract void WritePropertyRefElement(IEdmStructuralProperty property);
+        internal abstract void WritePropertyRefElement(IEdmPropertyRef propertyRef);
 
         internal abstract void WriteNavigationPropertyElementHeader(IEdmNavigationProperty property);
 
diff --git a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaXmlWriter.cs b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaXmlWriter.cs
index 075c68d7f8..8f9a97ac8d 100644
--- a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaXmlWriter.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSchemaXmlWriter.cs
@@ -150,10 +150,11 @@ internal override void WriteDeclaredKeyPropertiesElementHeader()
             this.xmlWriter.WriteStartElement(CsdlConstants.Element_Key);
         }
 
-        internal override void WritePropertyRefElement(IEdmStructuralProperty property)
+        internal override void WritePropertyRefElement(IEdmPropertyRef propertyRef)
         {
             this.xmlWriter.WriteStartElement(CsdlConstants.Element_PropertyRef);
-            this.WriteRequiredAttribute(CsdlConstants.Attribute_Name, property.Name, EdmValueWriter.StringAsXml);
+            this.WriteRequiredAttribute(CsdlConstants.Attribute_Name, propertyRef.Name, EdmValueWriter.StringAsXml);
+            this.WriteOptionalAttribute(CsdlConstants.Attribute_Alias, propertyRef.PropertyAlias, EdmValueWriter.StringAsXml);
             this.WriteEndElement();
         }
 
diff --git a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSerializationVisitor.cs b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSerializationVisitor.cs
index 45b618822f..c317b3f99e 100644
--- a/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSerializationVisitor.cs
+++ b/src/Microsoft.OData.Edm/Csdl/Serialization/EdmModelCsdlSerializationVisitor.cs
@@ -145,7 +145,7 @@ protected override void ProcessEntityType(IEdmEntityType element)
             this.BeginElement(element, this.schemaWriter.WriteEntityTypeElementHeader);
             if (element.DeclaredKey != null && element.DeclaredKey.Any())
             {
-                this.VisitEntityTypeDeclaredKey(element.DeclaredKey);
+                this.VisitEntityTypeDeclaredKey(element.DeclaredKeyRef());
             }
 
             this.VisitProperties(element.DeclaredStructuralProperties().Cast<IEdmProperty>());
@@ -680,18 +680,18 @@ private void ProcessFacets(IEdmTypeReference element, bool inlineType)
             }
         }
 
-        private void VisitEntityTypeDeclaredKey(IEnumerable<IEdmStructuralProperty> keyProperties)
+        private void VisitEntityTypeDeclaredKey(IEnumerable<IEdmPropertyRef> keyProperties)
         {
             this.schemaWriter.WriteDeclaredKeyPropertiesElementHeader();
             this.VisitPropertyRefs(keyProperties);
             this.schemaWriter.WriteArrayEndElement();
         }
 
-        private void VisitPropertyRefs(IEnumerable<IEdmStructuralProperty> properties)
+        private void VisitPropertyRefs(IEnumerable<IEdmPropertyRef> properties)
         {
-            foreach (IEdmStructuralProperty property in properties)
+            foreach (IEdmPropertyRef propertyRef in properties)
             {
-                this.schemaWriter.WritePropertyRefElement(property);
+                this.schemaWriter.WritePropertyRefElement(propertyRef);
             }
         }
 
diff --git a/src/Microsoft.OData.Edm/ExtensionMethods/ExtensionMethods.cs b/src/Microsoft.OData.Edm/ExtensionMethods/ExtensionMethods.cs
index a69c3bf04e..49cb818a8c 100644
--- a/src/Microsoft.OData.Edm/ExtensionMethods/ExtensionMethods.cs
+++ b/src/Microsoft.OData.Edm/ExtensionMethods/ExtensionMethods.cs
@@ -2124,6 +2124,52 @@ public static IEnumerable<IEdmStructuralProperty> Key(this IEdmEntityType type)
             return Enumerable.Empty<IEdmStructuralProperty>();
         }
 
+        /// <summary>
+        /// Gets the declared key ref of the most defined entity with a declared key present.
+        /// </summary>
+        /// <param name="type">Reference to the calling object.</param>
+        /// <returns>Key ref of this type.</returns>
+        public static IEnumerable<IEdmPropertyRef> KeyRef(this IEdmEntityType type)
+        {
+            EdmUtil.CheckArgumentNull(type, "type");
+            IEdmEntityType checkingType = type;
+            while (checkingType != null)
+            {
+                IEnumerable<IEdmPropertyRef> keyRefs = checkingType.DeclaredKeyRef();
+
+                if (keyRefs != null)
+                {
+                    return keyRefs;
+                }
+
+                checkingType = checkingType.BaseEntityType();
+            }
+
+            return Enumerable.Empty<IEdmPropertyRef>();
+        }
+
+        /// <summary>
+        /// Gets the declared key ref on a defined entity.
+        /// </summary>
+        /// <param name="type">Reference to the calling object.</param>
+        /// <returns>Key ref of this type.</returns>
+        public static IEnumerable<IEdmPropertyRef> DeclaredKeyRef(this IEdmEntityType entityType)
+        {
+            EdmUtil.CheckArgumentNull(entityType, "entityType");
+
+            if (entityType is IEdmKeyPropertyRef keyPropertyRef)
+            {
+                return keyPropertyRef.DeclaredKeyRef;
+            }
+
+            if (entityType.DeclaredKey == null)
+            {
+                return null;
+            }
+
+            return entityType.DeclaredKey.Select(k => new EdmPropertyRef(k));
+        }
+
         /// <summary>
         /// Determines whether the specified property is a key for its contained type.
         /// </summary>
diff --git a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.cs b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.cs
index 08ecc83344..288c5c86a7 100644
--- a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.cs
+++ b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.cs
@@ -299,6 +299,7 @@ internal sealed class EdmRes {
         internal const string Bad_UnresolvedEnumType = "Bad_UnresolvedEnumType";
         internal const string Bad_UnresolvedEnumMember = "Bad_UnresolvedEnumMember";
         internal const string Bad_UnresolvedProperty = "Bad_UnresolvedProperty";
+        internal const string Bad_UnresolvedPropertyRef = "Bad_UnresolvedPropertyRef";
         internal const string Bad_UnresolvedParameter = "Bad_UnresolvedParameter";
         internal const string Bad_UnresolvedReturn = "Bad_UnresolvedReturn";
         internal const string Bad_UnresolvedLabeledElement = "Bad_UnresolvedLabeledElement";
diff --git a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.csproj b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.csproj
index 656049f997..6fbd387f73 100644
--- a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.csproj
+++ b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.csproj
@@ -112,4 +112,17 @@
     <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Update="Microsoft.OData.Edm.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Microsoft.OData.Edm.tt</DependentUpon>
+    </Compile>
+    <Compile Update="Parameterized.Microsoft.OData.Edm.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>Parameterized.Microsoft.OData.Edm.tt</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
 </Project>
diff --git a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.txt b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.txt
index 146b3339d8..85bdcf2757 100644
--- a/src/Microsoft.OData.Edm/Microsoft.OData.Edm.txt
+++ b/src/Microsoft.OData.Edm/Microsoft.OData.Edm.txt
@@ -302,6 +302,7 @@ Bad_UnresolvedEntityContainer=The entity container '{0}' could not be found.
 Bad_UnresolvedEnumType=The enum type '{0}' could not be found.
 Bad_UnresolvedEnumMember=The enum member '{0}' could not be found.
 Bad_UnresolvedProperty=The property '{0}' could not be found.
+Bad_UnresolvedPropertyRef=The property ref on type '{0}' with name '{1}' and alias '{2}' could not be resolved.
 Bad_UnresolvedParameter=The parameter '{0}' could not be found.
 Bad_UnresolvedReturn=The return of operation '{0}' could not be found.
 Bad_UnresolvedLabeledElement=The labeled element '{0}' could not be found.
diff --git a/src/Microsoft.OData.Edm/Parameterized.Microsoft.OData.Edm.cs b/src/Microsoft.OData.Edm/Parameterized.Microsoft.OData.Edm.cs
index 11f6689f6a..27ec4c8cff 100644
--- a/src/Microsoft.OData.Edm/Parameterized.Microsoft.OData.Edm.cs
+++ b/src/Microsoft.OData.Edm/Parameterized.Microsoft.OData.Edm.cs
@@ -2393,6 +2393,14 @@ internal static string Bad_UnresolvedProperty(object p0)
             return Microsoft.OData.Edm.EdmRes.GetString(Microsoft.OData.Edm.EdmRes.Bad_UnresolvedProperty, p0);
         }
 
+        /// <summary>
+        /// A string like "The property ref on type '{0}' with name '{1}' and alias '{2}' could not be resolved."
+        /// </summary>
+        internal static string Bad_UnresolvedPropertyRef(object p0, object p1, object p2)
+        {
+            return Microsoft.OData.Edm.EdmRes.GetString(Microsoft.OData.Edm.EdmRes.Bad_UnresolvedPropertyRef, p0, p1, p2);
+        }
+
         /// <summary>
         /// A string like "The parameter '{0}' could not be found."
         /// </summary>
diff --git a/src/Microsoft.OData.Edm/PublicAPI/net45/PublicAPI.Unshipped.txt b/src/Microsoft.OData.Edm/PublicAPI/net45/PublicAPI.Unshipped.txt
index 5f282702bb..c71e219dc1 100644
--- a/src/Microsoft.OData.Edm/PublicAPI/net45/PublicAPI.Unshipped.txt
+++ b/src/Microsoft.OData.Edm/PublicAPI/net45/PublicAPI.Unshipped.txt
@@ -1 +1,18 @@
-
\ No newline at end of file
+Microsoft.OData.Edm.EdmEntityType.AddKeys(params Microsoft.OData.Edm.IEdmPropertyRef[] keyProperties) -> void
+Microsoft.OData.Edm.EdmEntityType.AddKeys(System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef> keyProperties) -> void
+Microsoft.OData.Edm.EdmPropertyRef
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string name, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.Name.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.IEdmKeyPropertyRef
+Microsoft.OData.Edm.IEdmKeyPropertyRef.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+Microsoft.OData.Edm.IEdmPropertyRef
+Microsoft.OData.Edm.IEdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.IEdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.Validation.EdmErrorCode.BadUnresolvedPropertyRef = 412 -> Microsoft.OData.Edm.Validation.EdmErrorCode
+static Microsoft.OData.Edm.ExtensionMethods.DeclaredKeyRef(this Microsoft.OData.Edm.IEdmEntityType entityType) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+static Microsoft.OData.Edm.ExtensionMethods.KeyRef(this Microsoft.OData.Edm.IEdmEntityType type) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+virtual Microsoft.OData.Edm.EdmEntityType.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
\ No newline at end of file
diff --git a/src/Microsoft.OData.Edm/PublicAPI/netstandard1.1/PublicAPI.Unshipped.txt b/src/Microsoft.OData.Edm/PublicAPI/netstandard1.1/PublicAPI.Unshipped.txt
index 5f282702bb..c71e219dc1 100644
--- a/src/Microsoft.OData.Edm/PublicAPI/netstandard1.1/PublicAPI.Unshipped.txt
+++ b/src/Microsoft.OData.Edm/PublicAPI/netstandard1.1/PublicAPI.Unshipped.txt
@@ -1 +1,18 @@
-
\ No newline at end of file
+Microsoft.OData.Edm.EdmEntityType.AddKeys(params Microsoft.OData.Edm.IEdmPropertyRef[] keyProperties) -> void
+Microsoft.OData.Edm.EdmEntityType.AddKeys(System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef> keyProperties) -> void
+Microsoft.OData.Edm.EdmPropertyRef
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string name, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.Name.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.IEdmKeyPropertyRef
+Microsoft.OData.Edm.IEdmKeyPropertyRef.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+Microsoft.OData.Edm.IEdmPropertyRef
+Microsoft.OData.Edm.IEdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.IEdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.Validation.EdmErrorCode.BadUnresolvedPropertyRef = 412 -> Microsoft.OData.Edm.Validation.EdmErrorCode
+static Microsoft.OData.Edm.ExtensionMethods.DeclaredKeyRef(this Microsoft.OData.Edm.IEdmEntityType entityType) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+static Microsoft.OData.Edm.ExtensionMethods.KeyRef(this Microsoft.OData.Edm.IEdmEntityType type) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+virtual Microsoft.OData.Edm.EdmEntityType.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
\ No newline at end of file
diff --git a/src/Microsoft.OData.Edm/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt b/src/Microsoft.OData.Edm/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
index 5f282702bb..c71e219dc1 100644
--- a/src/Microsoft.OData.Edm/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
+++ b/src/Microsoft.OData.Edm/PublicAPI/netstandard2.0/PublicAPI.Unshipped.txt
@@ -1 +1,18 @@
-
\ No newline at end of file
+Microsoft.OData.Edm.EdmEntityType.AddKeys(params Microsoft.OData.Edm.IEdmPropertyRef[] keyProperties) -> void
+Microsoft.OData.Edm.EdmEntityType.AddKeys(System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef> keyProperties) -> void
+Microsoft.OData.Edm.EdmPropertyRef
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.EdmPropertyRef(Microsoft.OData.Edm.IEdmStructuralProperty property, string name, string alias) -> void
+Microsoft.OData.Edm.EdmPropertyRef.Name.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.EdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.IEdmKeyPropertyRef
+Microsoft.OData.Edm.IEdmKeyPropertyRef.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+Microsoft.OData.Edm.IEdmPropertyRef
+Microsoft.OData.Edm.IEdmPropertyRef.PropertyAlias.get -> string
+Microsoft.OData.Edm.IEdmPropertyRef.ReferencedProperty.get -> Microsoft.OData.Edm.IEdmStructuralProperty
+Microsoft.OData.Edm.Validation.EdmErrorCode.BadUnresolvedPropertyRef = 412 -> Microsoft.OData.Edm.Validation.EdmErrorCode
+static Microsoft.OData.Edm.ExtensionMethods.DeclaredKeyRef(this Microsoft.OData.Edm.IEdmEntityType entityType) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+static Microsoft.OData.Edm.ExtensionMethods.KeyRef(this Microsoft.OData.Edm.IEdmEntityType type) -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
+virtual Microsoft.OData.Edm.EdmEntityType.DeclaredKeyRef.get -> System.Collections.Generic.IEnumerable<Microsoft.OData.Edm.IEdmPropertyRef>
\ No newline at end of file
diff --git a/src/Microsoft.OData.Edm/Schema/BadEntityType.cs b/src/Microsoft.OData.Edm/Schema/BadEntityType.cs
index 0f879ceb02..80fa4c3ee6 100644
--- a/src/Microsoft.OData.Edm/Schema/BadEntityType.cs
+++ b/src/Microsoft.OData.Edm/Schema/BadEntityType.cs
@@ -6,33 +6,26 @@
 
 using System.Collections.Generic;
 using Microsoft.OData.Edm.Validation;
-using Microsoft.OData.Edm.Vocabularies;
 
 namespace Microsoft.OData.Edm
 {
     /// <summary>
     /// Represents a semantically invalid EDM entity type.
     /// </summary>
-    internal class BadEntityType : BadNamedStructuredType, IEdmEntityType
+    internal class BadEntityType : BadNamedStructuredType, IEdmEntityType, IEdmKeyPropertyRef
     {
         public BadEntityType(string qualifiedName, IEnumerable<EdmError> errors)
             : base(qualifiedName, errors)
         {
         }
 
-        public IEnumerable<IEdmStructuralProperty> DeclaredKey
-        {
-            get { return null; }
-        }
+        public IEnumerable<IEdmStructuralProperty> DeclaredKey => null;
 
-        public override EdmTypeKind TypeKind
-        {
-            get { return EdmTypeKind.Entity; }
-        }
+        public IEnumerable<IEdmPropertyRef> DeclaredKeyRef => null;
+
+        public override EdmTypeKind TypeKind => EdmTypeKind.Entity;
+
+        public bool HasStream => false;
 
-        public bool HasStream
-        {
-            get { return false; }
-        }
     }
 }
diff --git a/src/Microsoft.OData.Edm/Schema/CoreModel/EdmCoreModelEntityType.cs b/src/Microsoft.OData.Edm/Schema/CoreModel/EdmCoreModelEntityType.cs
index ac497ae080..3ad35c4ee9 100644
--- a/src/Microsoft.OData.Edm/Schema/CoreModel/EdmCoreModelEntityType.cs
+++ b/src/Microsoft.OData.Edm/Schema/CoreModel/EdmCoreModelEntityType.cs
@@ -14,7 +14,7 @@ namespace Microsoft.OData.Edm
     /// <summary>
     /// The built-in Edm.EntityType abstract type in the core model.
     /// </summary>
-    internal sealed class EdmCoreModelEntityType : EdmType, IEdmEntityType, IEdmCoreModelElement, IEdmFullNamedElement
+    internal sealed class EdmCoreModelEntityType : EdmType, IEdmEntityType, IEdmCoreModelElement, IEdmFullNamedElement, IEdmKeyPropertyRef
     {
         /// <summary>
         /// The core Edm.EntityType singleton.
@@ -122,6 +122,11 @@ public IEnumerable<IEdmStructuralProperty> DeclaredKey
             get { return Enumerable.Empty<IEdmStructuralProperty>(); }
         }
 
+        /// <summary>
+        /// Gets the key property ref immediately within this type.
+        /// </summary>
+        public IEnumerable<IEdmPropertyRef> DeclaredKeyRef => Enumerable.Empty<IEdmPropertyRef>();
+
         /// <summary>
         /// Searches for a structural or navigation property with the given name in this type.
         /// </summary>
diff --git a/src/Microsoft.OData.Edm/Schema/EdmEntityType.cs b/src/Microsoft.OData.Edm/Schema/EdmEntityType.cs
index 56b36300b3..3fc6a1f858 100644
--- a/src/Microsoft.OData.Edm/Schema/EdmEntityType.cs
+++ b/src/Microsoft.OData.Edm/Schema/EdmEntityType.cs
@@ -7,19 +7,20 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 
 namespace Microsoft.OData.Edm
 {
     /// <summary>
     /// Represents a definition of an EDM entity type.
     /// </summary>
-    public class EdmEntityType : EdmStructuredType, IEdmEntityType, IEdmFullNamedElement
+    public class EdmEntityType : EdmStructuredType, IEdmEntityType, IEdmFullNamedElement, IEdmKeyPropertyRef
     {
         private readonly string namespaceName;
         private readonly string name;
         private readonly string fullName;
         private readonly bool hasStream;
-        private List<IEdmStructuralProperty> declaredKey;
+        private List<IEdmPropertyRef> declaredKey;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="EdmEntityType"/> class.
@@ -80,6 +81,14 @@ public EdmEntityType(string namespaceName, string name, IEdmEntityType baseType,
         /// Gets the structural properties of the entity type that make up the entity key.
         /// </summary>
         public virtual IEnumerable<IEdmStructuralProperty> DeclaredKey
+        {
+            get { return this.DeclaredKeyRef?.Select(k => k.ReferencedProperty); }
+        }
+
+        /// <summary>
+        /// Gets the property refs of the entity type that make up the entity key.
+        /// </summary>
+        public virtual IEnumerable<IEdmPropertyRef> DeclaredKeyRef
         {
             get { return this.declaredKey; }
         }
@@ -154,10 +163,39 @@ public void AddKeys(IEnumerable<IEdmStructuralProperty> keyProperties)
             {
                 if (this.declaredKey == null)
                 {
-                    this.declaredKey = new List<IEdmStructuralProperty>();
+                    this.declaredKey = new List<IEdmPropertyRef>();
+                }
+
+                // or, we should search if the property.DeclaringType != this
+                this.declaredKey.Add(new EdmPropertyRef(property));
+            }
+        }
+
+        /// <summary>
+        /// Adds the <paramref name="keyProperties"/> to the key of this entity type.
+        /// </summary>
+        /// <param name="keyProperties">The key properties.</param>
+        public void AddKeys(params IEdmPropertyRef[] keyProperties)
+        {
+            this.AddKeys((IEnumerable<IEdmPropertyRef>)keyProperties);
+        }
+
+        /// <summary>
+        /// Adds the <paramref name="keyProperties"/> to the key of this entity type.
+        /// </summary>
+        /// <param name="keyProperties">The key properties.</param>
+        public void AddKeys(IEnumerable<IEdmPropertyRef> keyProperties)
+        {
+            EdmUtil.CheckArgumentNull(keyProperties, "keyProperties");
+
+            foreach (IEdmPropertyRef propertyRef in keyProperties)
+            {
+                if (this.declaredKey == null)
+                {
+                    this.declaredKey = new List<IEdmPropertyRef>();
                 }
 
-                this.declaredKey.Add(property);
+                this.declaredKey.Add(propertyRef);
             }
         }
 
diff --git a/src/Microsoft.OData.Edm/Schema/EdmPropertyRef.cs b/src/Microsoft.OData.Edm/Schema/EdmPropertyRef.cs
new file mode 100644
index 0000000000..8cb72e0abb
--- /dev/null
+++ b/src/Microsoft.OData.Edm/Schema/EdmPropertyRef.cs
@@ -0,0 +1,64 @@
+//---------------------------------------------------------------------
+// <copyright file="EdmPropertyRef.cs" company="Microsoft">
+//      Copyright (C) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+// </copyright>
+//---------------------------------------------------------------------
+
+namespace Microsoft.OData.Edm
+{
+    /// <summary>
+    /// Represents a definition of an EDM property reference element.
+    /// </summary>
+    public class EdmPropertyRef : IEdmPropertyRef
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EdmPropertyRef"/> class.
+        /// </summary>
+        /// <param name="property">The referenced property.</param>
+        public EdmPropertyRef(IEdmStructuralProperty property)
+            : this(property, property?.Name, alias: null)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EdmPropertyRef"/> class.
+        /// </summary>
+        /// <param name="property">The referenced property.</param>
+        /// <param name="alias">The property reference alias.</param>
+        public EdmPropertyRef(IEdmStructuralProperty property, string alias)
+            : this(property, property?.Name, alias)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EdmPropertyRef"/> class.
+        /// </summary>
+        /// <param name="property">The referenced property.</param>
+        /// <param name="name">The property reference name.</param>
+        /// <param name="alias">The property reference alias.</param>
+        public EdmPropertyRef(IEdmStructuralProperty property, string name, string alias)
+        {
+            EdmUtil.CheckArgumentNull(property, "property");
+            EdmUtil.CheckArgumentNull(name, "name");
+
+            ReferencedProperty = property;
+            Name = name;
+            PropertyAlias = alias;
+        }
+
+        /// <summary>
+        /// Gets the referenced property.
+        /// </summary>
+        public IEdmStructuralProperty ReferencedProperty { get; }
+
+        /// <summary>
+        /// Gets the value of Name is a path expression leading to a primitive property.
+        /// </summary>
+        public string Name { get; }
+
+        /// <summary>
+        /// Gets the alias.
+        /// </summary>
+        public string PropertyAlias { get; }
+    }
+}
diff --git a/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmKeyPropertyRef.cs b/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmKeyPropertyRef.cs
new file mode 100644
index 0000000000..e557b7ccc0
--- /dev/null
+++ b/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmKeyPropertyRef.cs
@@ -0,0 +1,22 @@
+//---------------------------------------------------------------------
+// <copyright file="IEdmKeyPropertyRef.cs" company="Microsoft">
+//      Copyright (C) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+// </copyright>
+//---------------------------------------------------------------------
+
+using System.Collections.Generic;
+
+namespace Microsoft.OData.Edm
+{
+    /// <summary>
+    /// Represents a definition of key references of an entity type.
+    /// In the next major release, we should remove this interface and move the members into IEdmEntityType.
+    /// </summary>
+    public interface IEdmKeyPropertyRef
+    {
+        /// <summary>
+        /// Gets the declared key references.
+        /// </summary>
+        IEnumerable<IEdmPropertyRef> DeclaredKeyRef { get; }
+    }
+}
diff --git a/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmPropertyRef.cs b/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmPropertyRef.cs
new file mode 100644
index 0000000000..217a653cfd
--- /dev/null
+++ b/src/Microsoft.OData.Edm/Schema/Interfaces/IEdmPropertyRef.cs
@@ -0,0 +1,25 @@
+//---------------------------------------------------------------------
+// <copyright file="IEdmPropertyRef.cs" company="Microsoft">
+//      Copyright (C) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.
+// </copyright>
+//---------------------------------------------------------------------
+
+namespace Microsoft.OData.Edm
+{
+    /// <summary>
+    /// Represents a property reference element.
+    /// The edm:PropertyRef element MUST contain the Name attribute and MAY contain the Alias attribute.
+    /// </summary>
+    public interface IEdmPropertyRef : IEdmNamedElement
+    {
+        /// <summary>
+        /// Gets the property referenced structural property.
+        /// </summary>
+        IEdmStructuralProperty ReferencedProperty { get; }
+
+        /// <summary>
+        /// Gets the value of Alias
+        /// </summary>
+        string PropertyAlias { get; }
+    }
+}
diff --git a/src/Microsoft.OData.Edm/Validation/EdmErrorCode.cs b/src/Microsoft.OData.Edm/Validation/EdmErrorCode.cs
index e81a1ae560..7bce4fb0db 100644
--- a/src/Microsoft.OData.Edm/Validation/EdmErrorCode.cs
+++ b/src/Microsoft.OData.Edm/Validation/EdmErrorCode.cs
@@ -1437,5 +1437,10 @@ public enum EdmErrorCode
         /// A recursive complex-typed property must be optional.
         /// </summary>
         RecursiveComplexTypedPropertyMustBeOptional,
+
+        /// <summary>
+        /// Could not resolve a property ref with that name
+        /// </summary>
+        BadUnresolvedPropertyRef,
     }
 }
diff --git a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderJsonTests.cs b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderJsonTests.cs
index 476759212f..189a15ae31 100644
--- a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderJsonTests.cs
+++ b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderJsonTests.cs
@@ -24,6 +24,56 @@ namespace Microsoft.OData.Edm.Tests.Csdl
 {
     public class CsdlReaderJsonTests
     {
+        [Fact]
+        public void ReadKeyAliasInJsonTest()
+        {
+            var jsonCsdl = @"{
+  ""$Version"": ""4.0"",
+  ""NS"": {
+    ""EntityInfo"": {
+      ""$Kind"": ""ComplexType"",
+      ""ID"": {
+        ""$Type"": ""Edm.Int32""
+      },
+      ""Created"": {
+        ""$Type"": ""Edm.DateTimeOffset"",
+        ""$Nullable"": true,
+        ""$Precision"": 0
+      }
+    },
+    ""Category"": {
+      ""$Kind"": ""EntityType"",
+      ""$Key"": [
+        ""ID"",
+        {
+          ""EntityInfoID"": ""Info/ID""
+        }
+      ],
+      ""Info"": {
+        ""$Type"": ""NS.EntityInfo""
+      },
+      ""Name"": {
+        ""$Nullable"": true
+      },
+      ""ID"": {}
+    }
+  }
+}";
+
+            IEdmModel model = Parse(jsonCsdl);
+
+            // Act & Assert
+            IEdmEntityType categoryType = model.SchemaElements.OfType<IEdmEntityType>().First();
+
+            // Two "ID" because the referenced property names are "ID" in entity type and complex type.
+            Assert.Equal(new string[] { "NS.Category.ID", "NS.EntityInfo.ID" },
+                categoryType.DeclaredKey.Select(k => $"{k.DeclaringType.FullTypeName()}.{k.Name}"));
+
+            IEnumerable<IEdmPropertyRef> propertyRefs = categoryType.DeclaredKeyRef();
+            Assert.Equal(new string[] { "ID", "Info/ID" }, propertyRefs.Select(k => k.Name));
+            Assert.Equal(new string[] { "--", "EntityInfoID" }, propertyRefs.Select(k => k.PropertyAlias ?? "--" ));
+        }
+
         [Fact]
         public void ReadNavigationPropertyPartnerInJsonTest()
         {
diff --git a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderTests.cs b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderTests.cs
index 95fcddd076..cf2e75afe4 100644
--- a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderTests.cs
+++ b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlReaderTests.cs
@@ -907,6 +907,45 @@ public void ParsingOptionalParametersShouldSucceed()
             Assert.Equal("Smith", optionalParamWithDefault.DefaultValueString);
         }
 
+        [Fact]
+        public void ParsingXmlWithKeyAliasOnPropertyOnComplex()
+        {
+            // Arrange
+            string csdlWithKeyAlias = "<?xml version=\"1.0\" encoding=\"utf-16\"?><edmx:Edmx Version=\"4.0\" xmlns:edmx=\"http://docs.oasis-open.org/odata/ns/edmx\">" +
+                "<edmx:DataServices><Schema Namespace=\"DefaultNs\" xmlns=\"http://docs.oasis-open.org/odata/ns/edm\">" +
+                  "<EntityType Name=\"EntityType\">" +
+                    "<Key>" +
+                      "<PropertyRef Alias=\"ComID\" Name=\"Info/ID\" />" +
+                    "</Key>" +
+                    "<Property Name=\"ID\" Type=\"Edm.String\" Nullable=\"false\" />" +
+                    "<Property Name=\"Info\" Type=\"DefaultNs.ComplexType\" Nullable=\"false\" />" +
+                  "</EntityType>" +
+                  "<ComplexType Name=\"ComplexType\">" +
+                    "<Property Name=\"ID\" Type=\"Edm.Int32\" Nullable=\"false\" />" +
+                  "</ComplexType>" +
+                  "</Schema>" +
+              "</edmx:DataServices>" +
+            "</edmx:Edmx>";
+
+            // Act
+            IEdmModel model = CsdlReader.Parse(XElement.Parse(csdlWithKeyAlias).CreateReader());
+
+            // Assert
+            // There's only one entity type and one complex type
+            IEdmEntityType entityType = model.SchemaElements.OfType<IEdmEntityType>().First();
+            IEdmComplexType complexType = model.SchemaElements.OfType<IEdmComplexType>().First();
+
+            IEdmProperty complexIdProperty = complexType.FindProperty("ID");
+
+            IEdmStructuralProperty keyProperty = Assert.Single(entityType.DeclaredKey);
+            Assert.Same(complexIdProperty, keyProperty);
+
+            IEdmPropertyRef keyPropertyRef = Assert.Single(entityType.DeclaredKeyRef());
+            Assert.Same(complexIdProperty, keyPropertyRef.ReferencedProperty);
+            Assert.Equal("Info/ID", keyPropertyRef.Name);
+            Assert.Equal("ComID", keyPropertyRef.PropertyAlias);
+        }
+
         [Theory]
         [InlineData(EdmVocabularyAnnotationSerializationLocation.Inline)]
         [InlineData(EdmVocabularyAnnotationSerializationLocation.OutOfLine)]
diff --git a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlWriterTests.cs b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlWriterTests.cs
index 2e25e35007..ccb4c6589e 100644
--- a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlWriterTests.cs
+++ b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/CsdlWriterTests.cs
@@ -2156,6 +2156,148 @@ public void CanWriteUrlEscapeFunction()
 }");
         }
 
+        [Fact]
+        public void CanWriteEntityType_WithASimpleKey_ReferencingAPropertyOfAComplex()
+        {
+            // Arrange
+            EdmModel model = new EdmModel();
+            EdmComplexType complex = new EdmComplexType("NS", "EntityInfo");
+            var key = complex.AddStructuralProperty("ID", EdmCoreModel.Instance.GetInt32(false));
+            complex.AddStructuralProperty("Created", EdmCoreModel.Instance.GetDateTimeOffset(true));
+            model.AddElement(complex);
+
+            EdmEntityType entity = new EdmEntityType("NS", "Category");
+            entity.AddStructuralProperty("Info", new EdmComplexTypeReference(complex, false));
+            entity.AddStructuralProperty("Name", EdmCoreModel.Instance.GetString(true));
+            model.AddElement(entity);
+            entity.AddKeys(new EdmPropertyRef(key, "Info/ID", "EntityInfoID"));
+
+            // Act & Assert for XML
+            WriteAndVerifyXml(model, "<?xml version=\"1.0\" encoding=\"utf-16\"?>" +
+            "<edmx:Edmx Version=\"4.0\" xmlns:edmx=\"http://docs.oasis-open.org/odata/ns/edmx\">" +
+              "<edmx:DataServices><Schema Namespace=\"NS\" xmlns=\"http://docs.oasis-open.org/odata/ns/edm\">" +
+                "<ComplexType Name=\"EntityInfo\">" +
+                  "<Property Name=\"ID\" Type=\"Edm.Int32\" Nullable=\"false\" />" +
+                  "<Property Name=\"Created\" Type=\"Edm.DateTimeOffset\" />" +
+                "</ComplexType>" +
+                "<EntityType Name=\"Category\">" +
+                  "<Key>" +
+                    "<PropertyRef Name=\"Info/ID\" Alias=\"EntityInfoID\" />" +
+                  "</Key>" +
+                  "<Property Name=\"Info\" Type=\"NS.EntityInfo\" Nullable=\"false\" />" +
+                  "<Property Name=\"Name\" Type=\"Edm.String\" />" +
+                "</EntityType></Schema>" +
+              "</edmx:DataServices>" +
+            "</edmx:Edmx>");
+
+            // Act & Assert for JSON
+            WriteAndVerifyJson(model, @"{
+  ""$Version"": ""4.0"",
+  ""NS"": {
+    ""EntityInfo"": {
+      ""$Kind"": ""ComplexType"",
+      ""ID"": {
+        ""$Type"": ""Edm.Int32""
+      },
+      ""Created"": {
+        ""$Type"": ""Edm.DateTimeOffset"",
+        ""$Nullable"": true,
+        ""$Precision"": 0
+      }
+    },
+    ""Category"": {
+      ""$Kind"": ""EntityType"",
+      ""$Key"": [
+        {
+          ""EntityInfoID"": ""Info/ID""
+        }
+      ],
+      ""Info"": {
+        ""$Type"": ""NS.EntityInfo""
+      },
+      ""Name"": {
+        ""$Nullable"": true
+      }
+    }
+  }
+}");
+        }
+
+        [Fact]
+        public void CanWriteEntityType_WithAMultipleKeys_ReferencingAPropertyOfAComplex()
+        {
+            // Arrange
+            EdmModel model = new EdmModel();
+            EdmComplexType complex = new EdmComplexType("NS", "EntityInfo");
+            var key = complex.AddStructuralProperty("ID", EdmCoreModel.Instance.GetInt32(false));
+            complex.AddStructuralProperty("Created", EdmCoreModel.Instance.GetDateTimeOffset(true));
+            model.AddElement(complex);
+
+            EdmEntityType entity = new EdmEntityType("NS", "Category");
+            entity.AddStructuralProperty("Info", new EdmComplexTypeReference(complex, false));
+            entity.AddStructuralProperty("Name", EdmCoreModel.Instance.GetString(true));
+            var id = entity.AddStructuralProperty("ID", EdmCoreModel.Instance.GetString(false));
+            model.AddElement(entity);
+            entity.AddKeys(
+                new EdmPropertyRef(id),
+                new EdmPropertyRef(key, "Info/ID", "EntityInfoID"));
+
+            // Act & Assert for XML
+            WriteAndVerifyXml(model, "<?xml version=\"1.0\" encoding=\"utf-16\"?>" +
+  "<edmx:Edmx Version=\"4.0\" xmlns:edmx=\"http://docs.oasis-open.org/odata/ns/edmx\">" +
+    "<edmx:DataServices><Schema Namespace=\"NS\" xmlns=\"http://docs.oasis-open.org/odata/ns/edm\">" +
+      "<ComplexType Name=\"EntityInfo\">" +
+        "<Property Name=\"ID\" Type=\"Edm.Int32\" Nullable=\"false\" />" +
+        "<Property Name=\"Created\" Type=\"Edm.DateTimeOffset\" />" +
+      "</ComplexType>" +
+      "<EntityType Name=\"Category\">" +
+        "<Key>" +
+          "<PropertyRef Name=\"ID\" />" +
+          "<PropertyRef Name=\"Info/ID\" Alias=\"EntityInfoID\" />" +
+        "</Key>" +
+        "<Property Name=\"Info\" Type=\"NS.EntityInfo\" Nullable=\"false\" />" +
+        "<Property Name=\"Name\" Type=\"Edm.String\" />" +
+        "<Property Name=\"ID\" Type=\"Edm.String\" Nullable=\"false\" />" +
+      "</EntityType>" +
+    "</Schema>" +
+  "</edmx:DataServices>" +
+"</edmx:Edmx>");
+
+            // Act & Assert for JSON
+            WriteAndVerifyJson(model, @"{
+  ""$Version"": ""4.0"",
+  ""NS"": {
+    ""EntityInfo"": {
+      ""$Kind"": ""ComplexType"",
+      ""ID"": {
+        ""$Type"": ""Edm.Int32""
+      },
+      ""Created"": {
+        ""$Type"": ""Edm.DateTimeOffset"",
+        ""$Nullable"": true,
+        ""$Precision"": 0
+      }
+    },
+    ""Category"": {
+      ""$Kind"": ""EntityType"",
+      ""$Key"": [
+        ""ID"",
+        {
+          ""EntityInfoID"": ""Info/ID""
+        }
+      ],
+      ""Info"": {
+        ""$Type"": ""NS.EntityInfo""
+      },
+      ""Name"": {
+        ""$Nullable"": true
+      },
+      ""ID"": {}
+    }
+  }
+}");
+        }
+
         [Fact]
         public void CanWriteAnnotationPathExpression()
         {
diff --git a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/Semantics/CsdlSemanticsNavigationPropertyTests.cs b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/Semantics/CsdlSemanticsNavigationPropertyTests.cs
index 7e212eef5a..cb4dc74c7e 100644
--- a/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/Semantics/CsdlSemanticsNavigationPropertyTests.cs
+++ b/test/FunctionalTests/Microsoft.OData.Edm.Tests/Csdl/Semantics/CsdlSemanticsNavigationPropertyTests.cs
@@ -37,7 +37,7 @@ public CsdlSemanticsNavigationPropertyTests()
 
             var idProperty = new CsdlProperty("ID", new CsdlNamedTypeReference("Edm.Int32", false, null), null, null);
             var fkProperty = new CsdlProperty("FK", new CsdlNamedTypeReference("Edm.Int32", false, null), null, null);
-            this.csdlEntityType = new CsdlEntityType("EntityType", null, false, false, false, new CsdlKey(new[] { new CsdlPropertyReference("ID", null) }, null), new[] { idProperty, fkProperty }, new[] { collectionProperty, referenceProperty, navigationWithoutPartner }, null);
+            this.csdlEntityType = new CsdlEntityType("EntityType", null, false, false, false, new CsdlKey(new[] { new CsdlPropertyReference("ID", null, null) }, null), new[] { idProperty, fkProperty }, new[] { collectionProperty, referenceProperty, navigationWithoutPartner }, null);
 
             var csdlSchema = new CsdlSchema("FQ.NS", null, null, new[] { this.csdlEntityType }, Enumerable.Empty<CsdlEnumType>(), Enumerable.Empty<CsdlOperation>(),Enumerable.Empty<CsdlTerm>(),Enumerable.Empty<CsdlEntityContainer>(),Enumerable.Empty<CsdlAnnotations>(), Enumerable.Empty<CsdlTypeDefinition>(), null);
             var csdlModel = new CsdlModel();