Not at all. I have done this many times before. VFP7 is installed in a different location than VFP6, so you can choose what version you want to work with at anytime. All files in VFP6 are virtually the same except for the menue files. These files will convert fine when you attempt to open them for the first time in VFP7, but if they are converted to VFP7, they can never be reopened in VFP6. You will also have to re deploy the VFP7 runtime libs to all workstations that do not have VFP7 installed on them. I would recommend making a backup of the app, converting it by opening the menu file and recompiling in VFP7 and do some unit testing in a test environment.