If you are using FileMaker 10 or newer you can use either the OnObjectExit or OnObjectSave script trigger to perform your script, but this type of change may not need any script at all to achieve. The details to how that would be done depend on your database design.
Thanks...forgot to mention I'm still in version 8.5
..and also, both have simple, short value lists (not lists coming from other tables)
But how do you know that "Jim" is the name to put in field two when you select "red" in the first field?
Here's one way (and this worked way back in FileMaker 3, so it'll work with 8.5):
Define a table of team members with at least these fields:
Define a relationship to your layout's table (I'll call it "main") like this:
Main::ColorDropDownField = TeamMembers::Color
In place of your second drop down, put the Name field from TeamMembers on your layout.
If you have this record in Team Members:
Name: Jim Smith
Then selecting "Red" in the color drop down field in Main will result in "Jim Smith" appearing in the Name field.
It's also possible to use a looked up value field option to copy the name to a text field in Main. This can useful if you sometimes need to change the Team Member name without changing the color selected or if you want the member names in Main to remain unchanged if you later update the values in Color in the TeamMember table.
AHA I think that will work! Thanks so much...I'm ready to upgrade, there seem to be a lot more efficiencies in the newer versions!