How can I create a button which opens a new form and automatically populates one of the fields on the new form with data from a field on the previous form?

If you're using 2000, you can link the two tables (or queries) on which the forms are based in the relationship screen (choose "enforce referential integrity") and then make your second form a linked form with a button on the main form.

If you're using 98, I don't know what you do.

Good luck

Thanks. But, no, I have Access 97 not 2000.
When I enforce referencial integrity, on opening the new form I am told that there is not a corresponding record in the new table. What I'm trying to do is automatically create a corresponding record in the new table. Can you help?