Major Series Lacrosse (MSL) is a professional box lacrosse league in Canada, primarily based in Ontario. Founded in 1965, it features teams that compete for the prestigious Mann Cup, awarded to the national champion of senior men's lacrosse. The league showcases top talent, including many players who have competed at the international and collegiate levels. The MSL season typically runs from May to September, culminating in playoffs. Teams in the league include storied franchises like the Peterborough Lakers and the Brooklin Redmen. The league serves as a vital platform for the development of lacrosse in Canada and contributes to the sport's growing popularity.