A native of Arnold, Maryland, Toomey initially attended Martin Spalding High School before reclassifying and playing a fifth prep year at the Boys' Latin School of Maryland.
[1][2] Toomey played college lacrosse for Loyola as a goalkeeper and helped bring them to the school's first NCAA final in 1990.
[3][4] Toomey was hired to at his alma mater, Loyola, as head coach on December 21, 2005.
[2] As head coach of the Greyhounds, he led the team to win the NCAA Division I lacrosse championship on May 28, 2012, completing the year with an 18 and 1 record.
Toomey was named the 2012 winner of the F. Morris Touchstone Award as the Division I Coach of the Year.