diff --git a/cpp/SampleCommands/SampleCommands.vcxproj b/cpp/SampleCommands/SampleCommands.vcxproj
index 131e85ef..b1dd47cd 100644
--- a/cpp/SampleCommands/SampleCommands.vcxproj
+++ b/cpp/SampleCommands/SampleCommands.vcxproj
@@ -28,6 +28,7 @@
     <ClCompile Include="cmdSampleFrameRails.cpp" />
     <ClCompile Include="cmdSampleGetMultipleSpecial.cpp" />
     <ClCompile Include="cmdSampleGrid.cpp" />
+    <ClCompile Include="cmdSampleGroupUserData.cpp" />
     <ClCompile Include="cmdSampleHidePoints.cpp" />
     <ClCompile Include="cmdSampleMappingUvwTransform.cpp" />
     <ClCompile Include="cmdSampleMergeSrf.cpp" />
diff --git a/cpp/SampleCommands/SampleCommands.vcxproj.filters b/cpp/SampleCommands/SampleCommands.vcxproj.filters
index e1198519..482bbd75 100644
--- a/cpp/SampleCommands/SampleCommands.vcxproj.filters
+++ b/cpp/SampleCommands/SampleCommands.vcxproj.filters
@@ -858,6 +858,9 @@
     <ClCompile Include="cmdSampleDrawSubD.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="cmdSampleGroupUserData.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="SampleCommandsApp.h">
diff --git a/cpp/SampleCommands/cmdSampleGroupUserData.cpp b/cpp/SampleCommands/cmdSampleGroupUserData.cpp
new file mode 100644
index 00000000..d5da49cc
--- /dev/null
+++ b/cpp/SampleCommands/cmdSampleGroupUserData.cpp
@@ -0,0 +1,308 @@
+#include "stdafx.h"
+#include "SampleCommandsPlugIn.h"
+
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+//
+// BEGIN CSampleGroupUserData
+//
+
+class CSampleGroupUserData : public ON_UserData
+{
+  ON_OBJECT_DECLARE(CSampleGroupUserData);
+
+public:
+  static ON_UUID Id();
+
+  CSampleGroupUserData();
+  ~CSampleGroupUserData() = default;
+  CSampleGroupUserData(const CSampleGroupUserData& src);
+  CSampleGroupUserData& operator=(const CSampleGroupUserData& src);
+
+  bool GetDescription(ON_wString& description) override;
+  bool Archive() const override;
+  bool Write(ON_BinaryArchive& binary_archive) const override;
+  bool Read(ON_BinaryArchive& binary_archive) override;
+
+public:
+  // Helper functions
+  static bool HasUserData(const CRhinoGroup* group);
+  static bool SetUserData(CRhinoDoc& doc, const CRhinoGroup* group);
+  static bool GetUserData(const CRhinoGroup* group, ON_wString& string);
+  static bool RemoveUserData(CRhinoDoc& doc, const CRhinoGroup* pRhinoGroup);
+
+public:
+  ON_wString m_string;
+};
+
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+
+ON_OBJECT_IMPLEMENT(CSampleGroupUserData, ON_UserData, "820A89D9-8AA5-48F2-8DAE-1A440F3A93CB");
+
+ON_UUID CSampleGroupUserData::Id()
+{
+  return ON_CLASS_ID(CSampleGroupUserData);
+}
+
+CSampleGroupUserData::CSampleGroupUserData()
+{
+  m_userdata_uuid = CSampleGroupUserData::Id();
+  m_application_uuid = SampleCommandsPlugIn().PlugInID();
+  m_userdata_copycount = 1; // enable copying
+  m_string = L"Hello Rhino Group!";
+}
+
+CSampleGroupUserData::CSampleGroupUserData(const CSampleGroupUserData& src)
+  : ON_UserData(src)
+{
+  m_userdata_uuid = CSampleGroupUserData::Id();
+  m_application_uuid = SampleCommandsPlugIn().PlugInID();
+  m_string = src.m_string;
+}
+
+CSampleGroupUserData& CSampleGroupUserData::operator=(const CSampleGroupUserData& src)
+{
+  if (this != &src)
+  {
+    ON_UserData::operator=(src);
+    m_string = src.m_string;
+  }
+  return *this;
+}
+
+bool CSampleGroupUserData::GetDescription(ON_wString& description)
+{
+  description = L"Sample Group User Data";
+  return true;
+}
+
+bool CSampleGroupUserData::Archive() const
+{
+  return true;
+}
+
+bool CSampleGroupUserData::Write(ON_BinaryArchive& binary_archive) const
+{
+  int minor_version = 0;
+  bool rc = binary_archive.BeginWrite3dmChunk(TCODE_ANONYMOUS_CHUNK, 1, minor_version);
+  if (!rc)
+    return false;
+
+  for (;;)
+  {
+    // version 1.0 fields
+    rc = binary_archive.WriteString(m_string);
+    if (!rc) break;
+
+    break;
+  }
+
+  if (!binary_archive.EndWrite3dmChunk())
+    rc = false;
+
+  return rc;
+}
+
+bool CSampleGroupUserData::Read(ON_BinaryArchive& binary_archive)
+{
+  int major_version = 0;
+  int minor_version = 0;
+  bool rc = binary_archive.BeginRead3dmChunk(TCODE_ANONYMOUS_CHUNK, &major_version, &minor_version);
+  if (!rc)
+    return false;
+
+  for (;;)
+  {
+    rc = (1 == major_version);
+    if (!rc) break;
+
+    // version 1.0 fields
+    rc = binary_archive.ReadString(m_string);
+    if (!rc) break;
+
+    break;
+  }
+
+  if (!binary_archive.EndRead3dmChunk())
+    rc = false;
+
+  return rc;
+}
+
+bool CSampleGroupUserData::HasUserData(const CRhinoGroup* group)
+{
+  if (nullptr != group)
+  {
+    CSampleGroupUserData* data = CSampleGroupUserData::Cast(group->GetUserData(CSampleGroupUserData::Id()));
+    return (nullptr != data);
+  }
+  return false;
+}
+
+bool CSampleGroupUserData::SetUserData(CRhinoDoc& doc, const CRhinoGroup* group)
+{
+  if (nullptr == group)
+    return false;
+
+  if (CSampleGroupUserData::HasUserData(group))
+    return true;
+
+  ON_Group new_group(*group);
+
+  CSampleGroupUserData* data = new CSampleGroupUserData();
+  if (!new_group.AttachUserData(data))
+  {
+    delete data;
+    return false;
+  }
+
+  return doc.m_group_table.ModifyGroup(new_group, group->Index(), false);
+}
+
+bool CSampleGroupUserData::GetUserData(const CRhinoGroup* group, ON_wString& string)
+{
+  if (nullptr != group)
+  {
+    CSampleGroupUserData* data = CSampleGroupUserData::Cast(group->GetUserData(CSampleGroupUserData::Id()));
+    if (nullptr != data)
+    {
+      string = data->m_string;
+      return true;
+    }
+  }
+  return false;
+}
+
+bool CSampleGroupUserData::RemoveUserData(CRhinoDoc& doc, const CRhinoGroup* group)
+{
+  if (nullptr == group)
+    return false;
+
+  if (!CSampleGroupUserData::HasUserData(group))
+    return false;
+
+  ON_Group new_group(*group);
+
+  CSampleGroupUserData* data = CSampleGroupUserData::Cast(new_group.GetUserData(CSampleGroupUserData::Id()));
+  if (nullptr != data)
+  {
+    new_group.DetachUserData(data);
+    delete data;
+    data = nullptr;
+    return doc.m_group_table.ModifyGroup(new_group, group->Index(), false);
+  }
+
+  return false;
+}
+
+//
+// END CSampleGroupUserData
+//
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+//
+// BEGIN SampleSetGroupUserData command
+//
+
+#pragma region SampleSetGroupUserData command
+
+class CCommandSampleSetGroupUserData : public CRhinoCommand
+{
+public:
+  CCommandSampleSetGroupUserData() = default;
+  UUID CommandUUID() override
+  {
+    // {9A8AE3FD-6413-4397-8303-EAD11954232E}
+    static const GUID SampleSetGroupUserDataCommand_UUID =
+    { 0x9a8ae3fd, 0x6413, 0x4397, { 0x83, 0x3, 0xea, 0xd1, 0x19, 0x54, 0x23, 0x2e } };
+    return SampleSetGroupUserDataCommand_UUID;
+  }
+  const wchar_t* EnglishCommandName() override { return L"SampleSetGroupUserData"; }
+  CRhinoCommand::result RunCommand(const CRhinoCommandContext& context) override;
+};
+
+// The one and only CCommandSampleSetGroupUserData object
+static class CCommandSampleSetGroupUserData theSampleSetGroupUserDataCommand;
+
+CRhinoCommand::result CCommandSampleSetGroupUserData::RunCommand(const CRhinoCommandContext& context)
+{
+  const CRhinoGroup* group = context.m_doc.m_group_table[0];
+  if (nullptr == group)
+  {
+    RhinoApp().Print(L"The document's group table is empty.\n");
+    return CRhinoCommand::nothing;
+  }
+
+  bool rc = CSampleGroupUserData::SetUserData(context.m_doc, group);
+  if (rc)
+    RhinoApp().Print(L"Group user data added successfully.\n");
+  else
+    RhinoApp().Print(L"Unable to add group user data.\n");
+
+  return CRhinoCommand::success;
+}
+
+#pragma endregion
+
+//
+// END SampleSetGroupUserData command
+//
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////
+//
+// BEGIN SampleGetGroupUserData command
+//
+
+#pragma region SampleGetGroupUserData command
+
+class CCommandSampleGetGroupUserData : public CRhinoCommand
+{
+public:
+  CCommandSampleGetGroupUserData() = default;
+  UUID CommandUUID() override
+  {
+    // {15C1B793-F9EB-4B9F-8591-CC467A360ED0}
+    static const GUID SampleGetGroupUserDataCommand_UUID =
+    { 0x15c1b793, 0xf9eb, 0x4b9f, { 0x85, 0x91, 0xcc, 0x46, 0x7a, 0x36, 0xe, 0xd0 } };
+    return SampleGetGroupUserDataCommand_UUID;
+  }
+  const wchar_t* EnglishCommandName() override { return L"SampleGetGroupUserData"; }
+  CRhinoCommand::result RunCommand(const CRhinoCommandContext& context) override;
+};
+
+// The one and only CCommandSampleGetGroupUserData object
+static class CCommandSampleGetGroupUserData theSampleGetGroupUserDataCommand;
+
+CRhinoCommand::result CCommandSampleGetGroupUserData::RunCommand(const CRhinoCommandContext& context)
+{
+  const CRhinoGroup* group = context.m_doc.m_group_table[0];
+  if (nullptr == group)
+  {
+    RhinoApp().Print(L"The document's group table is empty.\n");
+    return CRhinoCommand::nothing;
+  }
+
+  ON_wString string;
+  bool rc = CSampleGroupUserData::GetUserData(group, string);
+  if (rc)
+    RhinoApp().Print(L"Group has user data: %ls\n", static_cast<const wchar_t*>(string));
+  else
+    RhinoApp().Print(L"No group user data found.\n");
+
+  return CRhinoCommand::success;
+}
+
+#pragma endregion
+
+//
+// END SampleGetGroupUserData command
+//
+////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////