Born in Ogden, Utah, Monagan grew up in Vallejo, California and earned his Bachelor of Science in Business Administration in 1942 from the College of the Pacific (later the University of the Pacific), where he played basketball and was student body president.

From 1943 to 1946, including during World War II, he served as a United States Coast Guard officer, seeing duty in the Aleutian Islands.

After the 1970 elections, Monagan again became Assembly Republican Leader and held that post until becoming United States Assistant Secretary of Transportation in 1973, holding that position until 1974.

[1] In 1984, he left the CMTA to become president of the California Economic Development Corporation, serving until 1994.

[2] Monagan Hall is a student housing complex consisting of four-bedroom suites available only to juniors and seniors.