[2] O'Leary played on the youth team of League of Ireland Club, St. Patrick's Athletic.
"[3] He started his coaching career as an assistant at Boston College, and later the University of New Hampshire.
From 1989 to 1991, he served as the men's soccer head coach at Elmira College, where he posted a 38-11-2 record.
From 2001[4] to 2005, he served as the men's soccer head coach at George Mason University.
[10][11][12] In February 2015, O'Leary was named Men's Soccer Head Coach at the University of Massachusetts.