Previous posters are correct, this is typically a javascript task, which, as a web guy, I do all the time. However, in a recent project I am doing almost exactly what you decribe--one where user selections progressively narrow their options. My method is to have the user "Go" after selecting from the first set of options, which submits the form to my Perl script. The script uses the choice to tap the MySQL db and build the second set of choices and populate the next dropdown. This repeats a couple of more times. I do it all with HTML::Template, a wonderful module that is easy to use and perfect for this kind of thing--especially for those wanting to avoid javascript (not really my reason, but it's actually easier using Perl and H::T. Read up on HTML::Template in Tutorials or CPAN. Good luck.