diff --git a/src/csharp/Grpc.Core/Internal/AsyncCall.cs b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
index dadc9ab76cf..6f37b059f75 100644
--- a/src/csharp/Grpc.Core/Internal/AsyncCall.cs
+++ b/src/csharp/Grpc.Core/Internal/AsyncCall.cs
@@ -181,6 +181,7 @@ namespace Grpc.Core.Internal
             {
                 started = true;
                 halfcloseRequested = true;
+                halfclosed = true;  // halfclose not confirmed yet, but it will be once finishedHandler is called.
         
                 this.readObserver = readObserver;
 
@@ -544,6 +545,8 @@ namespace Grpc.Core.Internal
                     }
                     observer = readObserver;
                     status = finishedStatus;
+
+                    ReleaseResourcesIfPossible();
                 }
 
                 // TODO: wrap deserialization...
diff --git a/src/csharp/Grpc.Examples/MathServiceImpl.cs b/src/csharp/Grpc.Examples/MathServiceImpl.cs
index 462fab4454f..76a08ce5186 100644
--- a/src/csharp/Grpc.Examples/MathServiceImpl.cs
+++ b/src/csharp/Grpc.Examples/MathServiceImpl.cs
@@ -127,8 +127,7 @@ namespace math
 
             public void OnCompleted()
             {
-                Task.Factory.StartNew(() =>
-                    responseObserver.OnCompleted());
+                responseObserver.OnCompleted();
             }
 
             public void OnError(Exception error)
@@ -138,13 +137,7 @@ namespace math
 
             public void OnNext(DivArgs value)
             {
-                // TODO: currently we need this indirection because
-                // responseObserver waits for write to finish, this
-                // callback is called from grpc threadpool which
-                // currently only has one thread.
-                // Same story for OnCompleted().
-                Task.Factory.StartNew(() =>
-                responseObserver.OnNext(DivInternal(value)));
+                responseObserver.OnNext(DivInternal(value));
             }
         }
     }
diff --git a/src/csharp/Grpc.IntegrationTesting/Client.cs b/src/csharp/Grpc.IntegrationTesting/Client.cs
index 0c70744cea5..fa1c7cd051b 100644
--- a/src/csharp/Grpc.IntegrationTesting/Client.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Client.cs
@@ -138,7 +138,7 @@ namespace Grpc.IntegrationTesting
             }
         }
 
-        private void RunEmptyUnary(TestServiceGrpc.ITestServiceClient client)
+        public static void RunEmptyUnary(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running empty_unary");
             var response = client.EmptyCall(Empty.DefaultInstance);
@@ -146,7 +146,7 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("Passed!");
         }
 
-        private void RunLargeUnary(TestServiceGrpc.ITestServiceClient client)
+        public static void RunLargeUnary(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running large_unary");
             var request = SimpleRequest.CreateBuilder()
@@ -162,7 +162,7 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("Passed!");
         }
 
-        private void RunClientStreaming(TestServiceGrpc.ITestServiceClient client)
+        public static void RunClientStreaming(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running client_streaming");
 
@@ -181,7 +181,7 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("Passed!");
         }
 
-        private void RunServerStreaming(TestServiceGrpc.ITestServiceClient client)
+        public static void RunServerStreaming(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running server_streaming");
 
@@ -206,7 +206,7 @@ namespace Grpc.IntegrationTesting
             Console.WriteLine("Passed!");
         }
 
-        private void RunPingPong(TestServiceGrpc.ITestServiceClient client)
+        public static void RunPingPong(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running ping_pong");
 
@@ -235,7 +235,7 @@ namespace Grpc.IntegrationTesting
 
             inputs.OnNext(StreamingOutputCallRequest.CreateBuilder()
                           .SetResponseType(PayloadType.COMPRESSABLE)
-                          .AddResponseParameters(ResponseParameters.CreateBuilder().SetSize(2635))
+                          .AddResponseParameters(ResponseParameters.CreateBuilder().SetSize(2653))
                           .SetPayload(CreateZerosPayload(1828)).Build());
 
             response = recorder.Queue.Take();
@@ -252,13 +252,15 @@ namespace Grpc.IntegrationTesting
             Assert.AreEqual(PayloadType.COMPRESSABLE, response.Payload.Type);
             Assert.AreEqual(58979, response.Payload.Body.Length);
 
+            inputs.OnCompleted();
+
             recorder.Finished.Wait();
             Assert.AreEqual(0, recorder.Queue.Count);
 
             Console.WriteLine("Passed!");
         }
 
-        private void RunEmptyStream(TestServiceGrpc.ITestServiceClient client)
+        public static void RunEmptyStream(TestServiceGrpc.ITestServiceClient client)
         {
             Console.WriteLine("running empty_stream");
 
@@ -273,13 +275,13 @@ namespace Grpc.IntegrationTesting
         }
 
         // This is not an official interop test, but it's useful.
-        private void RunBenchmarkEmptyUnary(TestServiceGrpc.ITestServiceClient client)
+        public static void RunBenchmarkEmptyUnary(TestServiceGrpc.ITestServiceClient client)
         {
             BenchmarkUtil.RunBenchmark(10000, 10000,
                                        () => { client.EmptyCall(Empty.DefaultInstance);});
         }
 
-        private Payload CreateZerosPayload(int size) {
+        private static Payload CreateZerosPayload(int size) {
             return Payload.CreateBuilder().SetBody(ByteString.CopyFrom(new byte[size])).Build();
         }
 
diff --git a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
index 9b46a644bc1..e66f708a945 100644
--- a/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
+++ b/src/csharp/Grpc.IntegrationTesting/Grpc.IntegrationTesting.csproj
@@ -47,6 +47,8 @@
     <Compile Include="TestServiceGrpc.cs" />
     <Compile Include="Empty.cs" />
     <Compile Include="Messages.cs" />
+    <Compile Include="InteropClientServerTest.cs" />
+    <Compile Include="TestServiceImpl.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
new file mode 100644
index 00000000000..87d25b0a98c
--- /dev/null
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
@@ -0,0 +1,119 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+using Grpc.Core.Utils;
+using NUnit.Framework;
+using grpc.testing;
+
+namespace Grpc.IntegrationTesting
+{
+    /// <summary>
+    /// Runs interop tests in-process.
+    /// </summary>
+    public class InteropClientServerTest
+    {
+        string host = "localhost";
+        Server server;
+        Channel channel;
+        TestServiceGrpc.ITestServiceClient client;
+
+        [TestFixtureSetUp]
+        public void Init()
+        {
+            GrpcEnvironment.Initialize();
+
+            server = new Server();
+            server.AddServiceDefinition(TestServiceGrpc.BindService(new TestServiceImpl()));
+            int port = server.AddPort(host + ":0");
+            server.Start();
+            channel = new Channel(host + ":" + port);
+            client = TestServiceGrpc.NewStub(channel);
+        }
+
+        [TestFixtureTearDown]
+        public void Cleanup()
+        {
+            channel.Dispose();
+
+            server.ShutdownAsync().Wait();
+            GrpcEnvironment.Shutdown();
+        }
+
+        [Test]
+        public void EmptyUnary()
+        {
+            Client.RunEmptyUnary(client);
+        }
+
+        [Test]
+        public void LargeUnary()
+        {
+            Client.RunEmptyUnary(client);
+        }
+
+        [Test]
+        public void ClientStreaming()
+        {
+            Client.RunClientStreaming(client);
+        }
+
+        [Test]
+        public void ServerStreaming()
+        {
+            Client.RunServerStreaming(client);
+        }
+
+        [Test]
+        public void PingPong()
+        {
+            Client.RunPingPong(client);
+        }
+
+        [Test]
+        public void EmptyStream()
+        {
+            Client.RunEmptyStream(client);
+        }
+
+        // TODO: add cancel_after_begin
+
+        // TODO: add cancel_after_first_response
+
+    }
+}
+
diff --git a/src/csharp/Grpc.IntegrationTesting/TestServiceImpl.cs b/src/csharp/Grpc.IntegrationTesting/TestServiceImpl.cs
new file mode 100644
index 00000000000..176843b1305
--- /dev/null
+++ b/src/csharp/Grpc.IntegrationTesting/TestServiceImpl.cs
@@ -0,0 +1,140 @@
+#region Copyright notice and license
+
+// Copyright 2015, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Google.ProtocolBuffers;
+using Grpc.Core.Utils;
+
+namespace grpc.testing
+{
+    /// <summary>
+    /// Implementation of TestService server
+    /// </summary>
+    public class TestServiceImpl : TestServiceGrpc.ITestService
+    {
+        public void EmptyCall(Empty request, IObserver<Empty> responseObserver)
+        {
+            responseObserver.OnNext(Empty.DefaultInstance);
+            responseObserver.OnCompleted();
+        }
+
+        public void UnaryCall(SimpleRequest request, IObserver<SimpleResponse> responseObserver)
+        {
+            var response = SimpleResponse.CreateBuilder()
+                .SetPayload(CreateZerosPayload(request.ResponseSize)).Build();
+            //TODO: check we support ReponseType
+            responseObserver.OnNext(response);
+            responseObserver.OnCompleted();
+        }
+
+        public void StreamingOutputCall(StreamingOutputCallRequest request, IObserver<StreamingOutputCallResponse> responseObserver)
+        {
+            foreach(var responseParam in request.ResponseParametersList)
+            {
+                var response = StreamingOutputCallResponse.CreateBuilder()
+                    .SetPayload(CreateZerosPayload(responseParam.Size)).Build();
+                responseObserver.OnNext(response);
+            }
+            responseObserver.OnCompleted();
+        }
+
+        public IObserver<StreamingInputCallRequest> StreamingInputCall(IObserver<StreamingInputCallResponse> responseObserver)
+        {
+            var recorder = new RecordingObserver<StreamingInputCallRequest>();
+            Task.Run(() => {
+                int sum = 0;
+                foreach(var req in recorder.ToList().Result)
+                {
+                    sum += req.Payload.Body.Length;
+                }
+                var response = StreamingInputCallResponse.CreateBuilder()
+                    .SetAggregatedPayloadSize(sum).Build();
+                responseObserver.OnNext(response);
+                responseObserver.OnCompleted();
+            });
+            return recorder;
+        }
+
+        public IObserver<StreamingOutputCallRequest> FullDuplexCall(IObserver<StreamingOutputCallResponse> responseObserver)
+        {
+            return new FullDuplexObserver(responseObserver);
+        }
+
+        public IObserver<StreamingOutputCallRequest> HalfDuplexCall(IObserver<StreamingOutputCallResponse> responseObserver)
+        {
+            throw new NotImplementedException();
+        }
+
+        private class FullDuplexObserver : IObserver<StreamingOutputCallRequest> {
+
+            readonly IObserver<StreamingOutputCallResponse> responseObserver;
+
+            public FullDuplexObserver(IObserver<StreamingOutputCallResponse> responseObserver)
+            {
+                this.responseObserver = responseObserver;
+            }
+
+            public void OnCompleted()
+            {
+                responseObserver.OnCompleted();
+            }
+
+            public void OnError(Exception error)
+            {
+                throw new NotImplementedException();
+            }
+
+            public void OnNext(StreamingOutputCallRequest value)
+            {
+                // TODO: this is not in order!!!
+                //Task.Factory.StartNew(() => {
+
+                    foreach(var responseParam in value.ResponseParametersList)
+                    {
+                        var response = StreamingOutputCallResponse.CreateBuilder()
+                            .SetPayload(CreateZerosPayload(responseParam.Size)).Build();
+                        responseObserver.OnNext(response);
+                    }
+                //});
+            }
+        }
+
+        private static Payload CreateZerosPayload(int size) {
+            return Payload.CreateBuilder().SetBody(ByteString.CopyFrom(new byte[size])).Build();
+        }
+    }
+}
+