The flag uses some elements of the family arms of General Richard Montgomery for whom the County was named. It is based on the shield of the official coat of arms of Montgomery County which was designed and approved by The College of Arms in London, England and officially adopted by Bill 38-76(now Section 1-402 of the County Code) enacted by the County Council on October 5, 1976 at the request of the County Executive.

The gold fleur-de-lis in two quarters of the flag are reminders of the French ancestry of the Montgomery family. The gold rings with blue gemstones in two quarters of the flag proclaim royal favor and protection and are found in the family coat of arms of General Montgomery's family.

The indented line which separates the upper quarters of the flag from the lower quarters of the flag represents the borders of a local government.

(Source: Montgomery County, "Our History and Government".)