I have a number of useful Visual Basic subroutines and functions which I'd like to make available to the Excel users in my office (all are non-VB or VBA users). I know these could be added as VBA subroutines and functions; however, I'd like to protect the security of my source code. I'd like to create Excel Add-In modules based upon my VB subroutines or functions. Are there useful books or web sites where I can get more information on the mechanics of building Excel Add-In, especially for a VB programer. Thanks in advance for your assistance.