Well basicly, the function names are the same in both the 16 bit dll and the 32 bit dll but one is 16 bit code and one is 32 bit code. The 16 bit version is loaded by LoadLibrary16 Probobly the best way to implement this is to make a cards.dll so that if its loaded by a 16 bit app or loaded via LoadLibrary16, it loads 16 bit code and provides the 16 bit version. If its loaded by LoadLibrary (or via an imports table) from a 32 bit app, the 32 bit version will be loaded. This way, it will work properly with all apps that use cards.dll (regardless of if they use the 16 bit or 32 bit versions) Although, I dont know if that would be a proper way to do it. Anyhow, I need some advice from the gurus on how best to handle this... BTW, there is at least one library that works with both versions by doing LoadLibrary and if that fails LoadLibrary16.