Mr. Mulhern was born in Upper Darby, PA, and graduated from Temple University before serving two years in the Army during the Korean War. He began working in the theatre as a box-office treasurer in Philadelphia, and also served in that capacity for ten seasons at the Bucks County Playhouse in New Hope, PA
In 1988 Mr. Mulhern signed on as general manager for Tony N' Tina's Wedding, the interactive piece of theatre. It became a steady job, running in New York for 20 years.
In 1975 Mr. Mulhern was general manager on a Jules Fieffer play called Knock Knock, about two Jewish men who are visited by Joan of Arc. The producer, a Spanish-born businesswoman named Adele Holtzer who was relatively new to producing, asked if the actress playing Joan could be backlit with rays of light. "If you have enough money," replied Mr. Mulhern, "you can do anything."
One week prior to his death, Mr. Mulhern was inducted into ATPAM’s Diamond Club for having served 50 years in the union.