diff --git a/README.md b/README.md
index b5f3964..4360851 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,7 @@ Setting | Required | Type | Description |
 `sheet_id` | Required | String | Your target google sheet id
 `stream_name` | Optional | String | Optionailly rename the stream and output file or table from the tap
 `child_sheet_name` | Optional | String | Optionally choose a different sheet from your Google Sheet file
+`key_properties` | Optional | Array of Strings | Optionally choose primary key column(s) from your Google Sheet file. Example: `["column_one", "column_two"]`
 
 ### Environment Variable
 
@@ -66,6 +67,7 @@ These settings expand into environment variables of:
 - `TAP_GOOGLE_SHEETS_SHEET_ID`
 - `TAP_GOOGLE_SHEETS_STREAM_NAME`
 - `TAP_GOOGLE_SHEETS_CHILD_SHEET_NAME`
+- `TAP_GOOGLE_SHEETS_KEY_PROPERTIES`
 
 ---
 
@@ -85,6 +87,8 @@ These settings expand into environment variables of:
 
 * The tap will again replace any spaces in column names with underscores.
 
+* When using the `key_properties` setting, you must choose columns with no null values.
+
 ### Loaders Tested
 
 - [target-jsonl](https://hub.meltano.com/targets/jsonl)
@@ -98,8 +102,6 @@ These settings expand into environment variables of:
 ## Roadmap
 
 - [ ] Add setting to optionally allow the selection of a range of data from a sheet. (Add an optional range setting).
-- [ ] Add setting to enable primary key, and select primary key(s) column(s).
-
 
 - [ ] Improve default behavior of a sheet with multiple columns of the same name and `target-postgres`.
 
@@ -114,7 +116,7 @@ Currently if have duplicate column names, a database will either:
 Use pip to install a release from GitHub.
 
 ```bash
-pip install git+https://github.com/Matatika/tap-shopify@vx.x.x
+pip install git+https://github.com/Matatika/tap-google-sheets@vx.x.x
 ```
 
 ## Usage
diff --git a/tap_google_sheets/tap.py b/tap_google_sheets/tap.py
index 3f88b14..f87c8ee 100644
--- a/tap_google_sheets/tap.py
+++ b/tap_google_sheets/tap.py
@@ -45,6 +45,12 @@ class TapGoogleSheets(Tap):
             + " your Google Sheet",
             required=False,
         ),
+        th.Property(
+            "key_properties",
+            th.ArrayType(th.StringType),
+            description="Optionally choose one or more primary key columns",
+            required=False,
+        ),
     ).to_dict()
 
     def discover_streams(self) -> List[Stream]:
@@ -53,6 +59,7 @@ def discover_streams(self) -> List[Stream]:
 
         stream_name = self.config.get("stream_name") or self.get_sheet_name()
         stream_name = stream_name.replace(" ", "_")
+        key_properties = self.config.get("key_properties", [])
 
         google_sheet_data = self.get_sheet_data()
 
@@ -68,6 +75,7 @@ def discover_streams(self) -> List[Stream]:
             )
             stream.child_sheet_name = child_sheet_name
             stream.selected
+            stream.primary_keys = key_properties
             streams.append(stream)
 
         return streams
diff --git a/tap_google_sheets/tests/test_ignoring_unnamed_columns.py b/tap_google_sheets/tests/test_ignoring_unnamed_columns.py
index a1b40f1..0ffda7c 100644
--- a/tap_google_sheets/tests/test_ignoring_unnamed_columns.py
+++ b/tap_google_sheets/tests/test_ignoring_unnamed_columns.py
@@ -22,7 +22,6 @@ def setUp(self):
 
     @responses.activate()
     def test_ignoring_unnamed_columns(self):
-
         self.missing_column_response = {
             "values": [
                 ["Column_One", "", "Column_Two"],
diff --git a/tap_google_sheets/tests/test_key_properties_setting.py b/tap_google_sheets/tests/test_key_properties_setting.py
new file mode 100644
index 0000000..531ebbc
--- /dev/null
+++ b/tap_google_sheets/tests/test_key_properties_setting.py
@@ -0,0 +1,57 @@
+"""Tests tap setting key_properties."""
+
+import unittest
+
+import responses
+
+from tap_google_sheets.tap import TapGoogleSheets
+
+
+class TestKeyPropertiesSetting(unittest.TestCase):
+    """Test class for tap setting key_properties"""
+
+    def setUp(self):
+        self.mock_config = {
+            "oauth_credentials": {
+                "client_id": "123",
+                "client_secret": "123",
+                "refresh_token": "123",
+            },
+            "sheet_id": "12345",
+        }
+        self.mock_config["key_properties"] = ["column_one", "column_two"]
+
+    @responses.activate()
+    def test_key_properties_being_set_in_stream(self):
+        """"""
+        self.column_response = {"values": [["Column One", "Column Two"], ["1", "1"]]}
+
+        responses.add(
+            responses.POST,
+            "https://oauth2.googleapis.com/token",
+            json={"access_token": "new_token"},
+            status=200,
+        ),
+        responses.add(
+            responses.GET,
+            "https://www.googleapis.com/drive/v2/files/12345",
+            json={"title": "File Name One"},
+            status=200,
+        ),
+        responses.add(
+            responses.GET,
+            "https://sheets.googleapis.com/v4/spreadsheets/12345/values/!1:1",
+            json={
+                "range": "!1:1",
+                "values": [["Column One", "Column Two"]],
+            },
+            status=200,
+        )
+
+        tap = TapGoogleSheets(config=self.mock_config)
+
+        # Assert that key_properties in tap streams equal to the setting key_properties
+        for stream in tap.catalog_dict.get("streams"):
+            self.assertEquals(
+                stream.get("key_properties"), tap.config.get("key_properties")
+            )
diff --git a/tap_google_sheets/tests/test_underscoring_column_names.py b/tap_google_sheets/tests/test_underscoring_column_names.py
index 9bd0010..5673bbf 100644
--- a/tap_google_sheets/tests/test_underscoring_column_names.py
+++ b/tap_google_sheets/tests/test_underscoring_column_names.py
@@ -22,7 +22,6 @@ def setUp(self):
 
     @responses.activate()
     def test_underscoring_column_names(self):
-
         self.column_response = {"values": [["Column One", "Column Two"], ["1", "1"]]}
 
         responses.add(