Learn how to register an assembly in the GAC.

1) Create an assembly key file Use the sn.exe tool to create a key file: sn -k StrongNameFile.snk If your path environment variables aren't set, you'll have to go to the C:\Program Files\Microsoft.NET\FrameworkSDK\Bin\ directory to run sn.exe) The filename "StrongNameFile.snk" can be any name you want. 2) Edit your assembly Now you have to add a tag which will link your assembly key to the assembly: using System.Reflection; [assembly:AssemblyKeyFile("StrongNameFile.snk")] Normally this is done in the utility AssemblyInfo.cs (vb) file. 3)Add your assembly to the GAC gacutil /i AssemblyFileName.dll To uninstall this assembly from the GAC, use the command: gacutil /u AssemblyFileName 4) (Opional) Add your assembly to machine.config Locate the <assemblies> tag (for web apps,under <configuration>/<system.web>/<compilation>/<compilers>/<assemblies>) Between the <assemblies> tags, enter: <add assembly="AssemblyFileName, Version=0.0.0.0, Culture=neutral, PublicKeyToken=5edf592a9c40680c" /> You can get the information for the assembly attribute, by running the gacutil /l command which will return a list of all the assemblies in the GAC. You will have to look for the one you just added and copy the entire line (less the Custom=XXX part at the end). At this point, you will be able to place this directive in your aspx pages. <%@Import Namespace="YourNamespace"%> or, you can set a reference in the Visual Studio IDE as you would with other GAC Assemblies.