Tim Gardner comes from the Philadelphia area where he attended The Episcopal Academy, earning varsity letters in letters in lacrosse, football, wrestling, and track. In 1993, he graduated from Williams College, where he earned his Bachelor's Degree in English, was a co-captain of the varsity lacrosse team, and played varsity football. He became a math teacher and an assistant lacrosse and football coach at several private schools in New England. In 1999, he earned his Master of Mathematics Education from Worcester Polytechnic Institute. He joined the Xaverian faculty in the 1998-1999 school year and became involved in the lacrosse and football programs.
Gardner became the head lacrosse coach at Xaverian in the 2000 season and has steered Xaverian's lacrosse program to four Catholic Conference Championships, three Massachusetts Division 1 state final games, and a Division 1 State Championship in 2013. He has coached nine All-American selections and two Academic All-Americans. Coach Gardner was named the Boston Globe Coach of the Year in 2007 and 2013, the BostonLax.net Coach of the Year in 2013, and has been named Catholic Conference Coach of the Year four times.