 <p>Look up in the registry to find the DLL associated with the ProgID you have. Once you have its full path, <a href="http://msdn.microsoft.com/en-us/library/1009fa28.aspx" rel="nofollow noreferrer">load</a> it as a normal .NET assembly:</p> <pre><code>var type = Type.GetTypeFromProgID("My.ProgId", true); var regPath = string.Format(@"{0}\CLSID\{1:B}\InProcServer32", Registry.ClassesRoot, type.GUID); var assemblyPath = Registry.GetValue(regPath, "", null); if (!string.IsNullOrEmpty(assemblyPath)) { var assembly = Assembly.LoadFrom(assemblyPath); // Use it as a normal .NET assembly } </code></pre>