VB Signature:

<DllImport("ole32.dll", ExactSpelling:=True, PreserveSig:=False)> _
Function CoCreateInstance( _
    ByRef clsid As Guid, _
    <MarshalAs(UnmanagedType.Interface)> ByVal punkOuter As Object, _
    ByVal context As Integer, _
    ByRef iid As Guid) _
    As <MarshalAs(UnmanagedType.Interface)> Object
End Function

C# Signature:

[DllImport("ole32.dll", ExactSpelling=true, PreserveSig=false)]
[return: MarshalAs(UnmanagedType.Interface)]
static extern object CoCreateInstance(
   [In, MarshalAs(UnmanagedType.LPStruct)] Guid rclsid,
   [MarshalAs(UnmanagedType.IUnknown)] object pUnkOuter,
   CLSCTX dwClsContext,
   [In, MarshalAs(UnmanagedType.LPStruct)] Guid riid);

Alternative Signature:

[DllImport("ole32.dll", EntryPoint = "CoCreateInstance", CallingConvention = CallingConvention.StdCall)]
static extern UInt32 CoCreateInstance([In, MarshalAs(UnmanagedType.LPStruct)] Guid rclsid,
   IntPtr pUnkOuter, UInt32 dwClsContext, [In, MarshalAs(UnmanagedType.LPStruct)] Guid riid,
   out IntPtr ppv);

User-Defined Types:

CLSCTX

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

Please add some!

Alternative Managed API:

Have a look at System.Activator.CreateInstance and its various overloads. Sample:

Guid CLSID_ShellDesktop = new Guid("00021400-0000-0000-C000-000000000046");
Type shellDesktopType = Type.GetTypeFromCLSID(CLSID_ShellDesktop, true);
object shellDesktop = Activator.CreateInstance(shellDesktopType);