A native of Rockaway, New Jersey, Gallagher attended Morris Catholic High School, where he graduated in 1969.
Gallagher's first college football coaching job was spent at Edinboro University of Pennsylvania for the 1984 and 1985 seasons as an offensive coordinator, followed by three years at Saint Francis and eight at William Paterson.
Through the 2009 college football season, Gallagher is the only William Paterson coach to guide his team to any playoff appearances.
Their abilities to hold blocks, pull with speed and to remember their assignments which are often given in pairs or threes for each play.
Gallagher saw the most success with this system most recently in the 2006 football system, where his Montville team matched up against West Essex High School in then-Giants Stadium for the Group III state championship, where he coached athletes such as John Gauweiler, Mike Todisco, and Chris Collins.