The U-18 boys and U-18 girls tournaments run through Sunday at the Optimist Fields off Hill Road.
There are five teams from Boise, Post Falls, Pocatello and Coeur d'Alene in the boys tournament, and four teams from Boise in the girls field.
The State Cup for U-13 to U-17 boys and girls is next weekend in Idaho Falls.
In addition to the State Cup in Boise this weekend, the 128-team Directors Cup is being played at the Optimist Fields.
The boys and girls teams from Idaho range from U-10 to U-18.