diff --git a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/AnalyzerReleases.Unshipped.md b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/AnalyzerReleases.Unshipped.md
index 17d4678ce..2bf896fda 100644
--- a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/AnalyzerReleases.Unshipped.md
+++ b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/AnalyzerReleases.Unshipped.md
@@ -1,2 +1,8 @@
 ; Unshipped analyzer release
 ; https://github.com/dotnet/roslyn-analyzers/blob/master/src/Microsoft.CodeAnalysis.Analyzers/ReleaseTrackingAnalyzers.Help.md
+
+### New Rules
+
+Rule ID | Category | Severity | Notes
+--------|----------|----------|-------
+AWSLambda0104 | AWSLambdaCSharpGenerator | Error | Missing reference to a required dependency
\ No newline at end of file
diff --git a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs
index f4e03856f..7455e4e0b 100644
--- a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs
+++ b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Diagnostics/DiagnosticDescriptors.cs
@@ -1,6 +1,4 @@
 using System;
-using System.Reflection.Metadata;
-using System.Runtime.InteropServices.ComTypes;
 using Microsoft.CodeAnalysis;
 
 namespace Amazon.Lambda.Annotations.SourceGenerator.Diagnostics
@@ -10,7 +8,7 @@ public static class DiagnosticDescriptors
         /// Generic errors
         public static readonly DiagnosticDescriptor UnhandledException = new DiagnosticDescriptor(id: "AWSLambda0001",
             title: "Unhandled exception",
-            messageFormat: $"This is a bug. Please run the build with detailed verbosity (dotnet build --verbosity detailed) and file a bug at https://github.com/aws/aws-lambda-dotnet with the build output and stack trace {{0}}.",
+            messageFormat: "This is a bug. Please run the build with detailed verbosity (dotnet build --verbosity detailed) and file a bug at https://github.com/aws/aws-lambda-dotnet with the build output and stack trace {0}.",
             category: "AWSLambda",
             DiagnosticSeverity.Error,
             isEnabledByDefault: true,
@@ -38,5 +36,13 @@ public static class DiagnosticDescriptors
             category: "AWSLambdaCSharpGenerator",
             DiagnosticSeverity.Info,
             isEnabledByDefault: true);
+        
+        public static readonly DiagnosticDescriptor MissingDependencies = new DiagnosticDescriptor(id: "AWSLambda0104",
+            title: "Missing reference to a required dependency",
+            messageFormat: "Your project has a missing required package dependency. Please add a reference to the following package: {0}",
+            category: "AWSLambdaCSharpGenerator",
+            DiagnosticSeverity.Error,
+            isEnabledByDefault: true);
+
     }
 }
\ No newline at end of file
diff --git a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Generator.cs b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Generator.cs
index b8d7d62b9..f421ead98 100644
--- a/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Generator.cs
+++ b/Libraries/src/Amazon.Lambda.Annotations.SourceGenerator/Generator.cs
@@ -74,6 +74,20 @@ public void Execute(GeneratorExecutionContext context)
                 foreach (var lambdaMethod in receiver.LambdaMethods)
                 {
                     var lambdaMethodModel = semanticModelProvider.GetMethodSemanticModel(lambdaMethod);
+                    
+                    // Check for necessary references
+                    if (lambdaMethodModel.HasAttribute(context, TypeFullNames.RestApiAttribute)
+                        || lambdaMethodModel.HasAttribute(context, TypeFullNames.HttpApiAttribute))
+                    {
+                        // Check for arbitrary type from "Amazon.Lambda.APIGatewayEvents"
+                        if (context.Compilation.ReferencedAssemblyNames.FirstOrDefault(x => x.Name == "Amazon.Lambda.APIGatewayEvents") == null)
+                        {
+                            diagnosticReporter.Report(Diagnostic.Create(DiagnosticDescriptors.MissingDependencies,
+                                lambdaMethod.GetLocation(),
+                                "Amazon.Lambda.APIGatewayEvents"));
+                        }
+                    }
+                    
                     var model = LambdaFunctionModelBuilder.Build(lambdaMethodModel, configureMethodModel, context);
 
                     // If there are more than one event, report them as errors