You can find the name of the OCX file by several means. The easiest in my opinion is to add the active X control to a form or class as an OLE control, then look at the property OleClass. For example the OleClass name of the treeview active x control is "MSComctlLib.treeCtrl2". The file name is MSCOMCTL.OCX. This information is also buried in the documetation but I found the documentation a long time after I found the file using this method. This file contains many active X controls as you may already know. I hope my explanation is clearer than mud and little helpful.