Paul,

As a general rule, yes...if you plan on using a form class across multiple projects, you'd want that in a library of reusable classes (concept would apply to other development platforms as well).

There should be examples in the MSDN help file for creating form classes...basically, you want to create a new project as a class library (as opposed to a windows app), then add a new item (a windows form), and then design your child form. When you build that project, a DLL will be created that you can then add as a reference in whatever project you need.

Kevin