diff --git a/impls/vbs/step3_env.vbs b/impls/vbs/step3_env.vbs
index 8ff0aeb374..5134e72f3f 100644
--- a/impls/vbs/step3_env.vbs
+++ b/impls/vbs/step3_env.vbs
@@ -129,11 +129,34 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(objCode, objEnv)
 	If TypeName(objCode) = "Nothing" Then
 		Set Evaluate = Nothing
 		Exit Function
 	End If
+
+	DebugEval objCode, objEnv
+
 	Dim varRet, objFirst
 	If objCode.Type = TYPES.LIST Then
 		If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step4_if_fn_do.vbs b/impls/vbs/step4_if_fn_do.vbs
index 37d364063a..6b3cccd3f9 100644
--- a/impls/vbs/step4_if_fn_do.vbs
+++ b/impls/vbs/step4_if_fn_do.vbs
@@ -143,11 +143,34 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(objCode, objEnv)
 	If TypeName(objCode) = "Nothing" Then
 		Set Evaluate = Nothing
 		Exit Function
 	End If
+
+	DebugEval objCode, objEnv
+
 	Dim varRet, objFirst
 	If objCode.Type = TYPES.LIST Then
 		If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step5_tco.vbs b/impls/vbs/step5_tco.vbs
index 1b23cadb8e..17d3449c29 100644
--- a/impls/vbs/step5_tco.vbs
+++ b/impls/vbs/step5_tco.vbs
@@ -152,6 +152,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -159,6 +179,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step6_file.vbs b/impls/vbs/step6_file.vbs
index 3bb1bdeeb5..02d58b5869 100644
--- a/impls/vbs/step6_file.vbs
+++ b/impls/vbs/step6_file.vbs
@@ -180,6 +180,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -187,6 +207,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step7_quote.vbs b/impls/vbs/step7_quote.vbs
index 5673f4a9ef..fd8aa9ebc9 100644
--- a/impls/vbs/step7_quote.vbs
+++ b/impls/vbs/step7_quote.vbs
@@ -303,6 +303,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -310,6 +330,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step8_macros.vbs b/impls/vbs/step8_macros.vbs
index 723f9a5b40..70f3bf755f 100644
--- a/impls/vbs/step8_macros.vbs
+++ b/impls/vbs/step8_macros.vbs
@@ -316,6 +316,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -323,6 +343,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/step9_try.vbs b/impls/vbs/step9_try.vbs
index 407cfee0e3..e346c3eea3 100644
--- a/impls/vbs/step9_try.vbs
+++ b/impls/vbs/step9_try.vbs
@@ -382,6 +382,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -389,6 +409,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()
diff --git a/impls/vbs/stepA_mal.vbs b/impls/vbs/stepA_mal.vbs
index 04b9626b49..0b93de67ad 100644
--- a/impls/vbs/stepA_mal.vbs
+++ b/impls/vbs/stepA_mal.vbs
@@ -383,6 +383,26 @@ Function Read(strCode)
 	Set Read = ReadString(strCode)
 End Function
 
+Sub DebugEval(objCode, objEnv)
+	Dim value, bool
+	Set value = objEnv.Get("DEBUG-EVAL")
+	If TypeName(value) = "Nothing" Then
+		bool = False
+	Else
+		Select Case value.Type
+			Case TYPES.NIL
+				bool = False
+			Case TYPES.BOOLEAN
+				bool = value.Value
+			Case Else
+				bool = True
+		End Select
+	End If
+	If bool Then
+		IO.WriteLine "EVAL: " + Print(objCode)
+	End If
+End Sub
+
 Function Evaluate(ByVal objCode, ByVal objEnv)
 	While True
 		If TypeName(objCode) = "Nothing" Then
@@ -390,6 +410,8 @@ Function Evaluate(ByVal objCode, ByVal objEnv)
 			Exit Function
 		End If
 
+		DebugEval objCode, objEnv
+
 		Dim varRet, objFirst
 		If objCode.Type = TYPES.LIST Then
 			If objCode.Count = 0 Then ' ()