John P. Gallagher earned an MBA from the University of Chicago Booth School of Business in 1947.
After graduating from high school in 1934, he worked at Commonwealth Edison Company for the next 10 years while attending evening courses at Northwestern University. He served as partner and vice president at Booz, Allen & Hamilton from 1946 to 1963, and as director of McKinsey & Company from 1963 to 1968. He joined Chemetron Corporation as president in 1968 and rose to become chairman, president, and CEO.
In 1977, he successfully resisted a widely publicized attempt by Crane Corporation to acquire Chemetron and negotiated a substantially more favorable merger with Allegheny Ludlum Industries, serving as an executive consultant to Chemetron in 1979.
Gallagher served as national chairman of the Chicago Booth Alumni Fund from 1974 to 1976 and as a member of the Council on Chicago Booth from its inception in 1968. He also served as director of the executive committee of the board of directors of the Community Renewal Society of Chicago, a member of the Citizens Board at Lake Forest College, and a trustee at Illinois Institute of Technology.