After the Korean War, where he served in the Air Force as an Intelligence Officer and achieved the rank of First Lieutenant, he went to work at NBC in New York.
Biography in: "Who's Who in Comedy" by Ronald L. Smith, pg. 207-208. New York: Facts on File, 1992. ISBN 0816023387
Earned a Bachelor of Arts degree from Fordham University (New York City, USA) in 1950.
Has a Masters Degree in Political Philosophy.
Has four children and three grandchildren
His son Patrick is an advertising executive living in Tucson; second son Michael is an actor; Terry is a pianist and composer; Tresa-Caitlin was a ballerina, whose credits include New York's Joffrey Ballet.
In addition to his skills as an actor, he is also an accomplished writer. His work includes twelve "One Day at a Time" scripts he wrote for the series.
Pro wrestler The Honky Tonk Man based his gimmick on the character (Duane Schneider) that Harrington played on "One Day at a Time" (1975).
Received his B.A. and M.A. from New York's Fordham University.
Son of Pat Harrington Sr.