The Sun Valley Boys Lacrosse team was founded in 1998 by students Kyle Garzia and Rory Logan. After successfully campaigning for the program, and with help from then-Athletic Director Sean Early and former Head Coach Chris Bell, the Vanguards entered 1998 in their year of Junior Varsity Competition. From 1999 thru 2008, the Vanguards competed in the now defunct Del Val league, taking home the league championship in 2003 and 2004. 2009 saw the Vanguards enter their first year of the ChestMont League, competing against schools such as Avon Grove, Bishop Shanahan, Kennett, Unionville, West Chester Rustin, West Chester Henderson, West Chester East, Great Valley, Downingtown East and Downingtown West. 2009 saw the Vanguards also qualify for the first time for the PIAA District 1 playoffs.