Boys Lacrosse in Saint Louis is played as a club high school sport and Missouri Scholastic Lacrosse Association (MSLA) runs both league play and the championships.
Girls high school lacrosse is run as an emerging sport by MSHSAA, however the girls league play and championships is run by MSLA. The web site for high school girls lacrosse is MO Girls Lax, not the MSLA site.
Both boys and girls club lacrosse is run by the Saint Louis Youth Lacrosse Association (SLYLA) which is the local affiliation of US Lacrosse. SLYLA runs a season end playoff for boys are girls.
Lacrosse is played in the spring for both club high school MSLA and club SLYLA, SLYLA club ends once kids are in high school. SLYLA club pre-high school teams are often affiliated with a high school program. Most SLYLA games are played at the same facilities where club soccer is played.