He was awarded the Distinguished Service Cross, the Purple Heart, the Legion of Merit, the Verdun Medal, the Légion d’Honneur[3] and the Croix de Guerre[4] with Palm for his actions in World War I. Muhlenberg served continuously in the regular army reserves for more than 20 years.

As an architect, Muhlenberg apprenticed with Charles Barton Keen, Magaziner & Potter, and John T. Windrim in Philadelphia.

[6] During the intervening years, to accommodate the reorganizations, the firm operated for various periods under the following names (dates, in some cases, are approximate):[7] In the 1950s, Muhlenberg was elected a Fellow of the American Institute of Architects.

[12] Muhlenberg served on the Reading City Council from 1932–1936,[13] and he was a councilman for the Borough of Wernersville during the 1920s, where he returned to live in his later years.

[16] A collection of awards, military medals, paperwork and other items related to Representative Muhlenberg is held by the Historical Society of Berks County.

Frederick Muhlenberg served as chairman for numerous civic and professional organizations, including the Association of Schuylkill River Municipalities, director of the American Red Cross Berks County Chapter (1929-), chairman of the Red Cross Disaster Relief Commission (1935), the State Board of Examiners of Architects, president of the Social Welfare League (1922–1935),[17] Public Charities Association (1927-),[4] and the State Art Commission (1952–1963).

[4][16] Listed in Who's Who in America, Muhlenberg received scores of educational, civilian, military and social service awards, including: