I need help on making a list box do a specific action.

Say i had a list box A with options "foo" and "bewm"
and another list box B with option "bar" "monkey" "spank" "luser" and "phear"

My question is what would I have to do in order to make it so when someone clicks on the option "foo" in list box A that when they look at the contents of B that they would be limited to only "bar" and "phear"
and if they clicked option "bewm" in list box A that in list box B the only available options would be "monkey" "spank" and "luser"

so basically what i need to know is how to limit the contents of one list box based on what was selected in another.

if you need more details let me know.

Thanks!

the recordsource for the second is a query who's criteria is the selected fields in the first.