I have 2 combo boxes, and I want the list in Combo box 2 to be governed by the selection in combo box 1

For example...

Combo Box 1 (Country)

France
Germany
United States
United Kingdom

Combo Box 2 (City)
(If United Kingdom is picked)
London
Manchester
Birmingham
etc...

(If United States is picked)
Los Angeles
New York
San Francisco
etc...

Is there a way of doing this?