Populating a drop down box based on another drop down box selection

Good day all;

On a form I am designing I have 2 drop down menus labeled, directorate and division.

What I would like to do is when the user selects a directorate, the division drop down is only populated with a list of divisions that belong to the selected directorate.

I am sure I have seen this question asked before, but, I am at a loss to find it…..

Thanks All

Chomp