The Mount Si Lacrosse Club was formed in 2010. The Club is a recognized tax exempt charitable organization under Section 501(c)(3) of the Internal Revenue Code. The Boys High School program is a member of the Evergreen Conference of High School Boys Division 2, which also includes Redmond, Union, Liberty, and Overlake. The youth program was also formed in 2010 and played their first year under the Snoqualmie Valley Youth Lacrosse name. The youth program was also part of Issaquah Youth Lacrosse in its inaugural year.