He played college football for the Michigan Wolverines, earning consensus All-American honors in 1973.

He was a consensus first-team All-American as a senior, was also selected twice to the All-Big Ten Academic squad, and was also a recipient of a National Football Foundation and College Football Hall of Fame postgraduate scholarship.

He had planned to attend medical school, but decided to forgo that to play professional football.

[2] He played five years in the NFL for the Chicago Bears (1974), the New York Giants (1975–1976).

[4] In 2005, Gallagher was selected as one of the 100 greatest Michigan football players of all time by the "Motown Sports Revival," ranking 65th on the all-time team.