The Interstate Box Lacrosse Association (IBLA) is the nation's largest adult box lacrosse league. The IBLA was formed to ultimately unify the system of Regional Box Lacrosse Leagues (RBLL) around the country. Each RBLL is its own state-wide league for the senior level of lacrosse for ages 18+ The Interstate Box Lacrosse Association (IBLA) is the nation's largest adult box lacrosse league. The IBLA was formed to ultimately unify the system of Regional Box Lacrosse Leagues (RBLL) around the country.

Each RBLL is its own state-wide league for the senior level of lacrosse for ages 18+ players. All RBLL's in each state use the same set of rules and follow similar regular season and playoff structures. These commonalities across all RBLL's is what brought the unification of the IBLA. In addition, the winner of each RBLL region each season, is granted the prestigious spot to compete in the IBLA Nationals. They play against the winner of each region within the IBLA network across the country.. All RBLL's in each state use the same set of rules and follow similar regular season and playoff structures. These commonalities across all RBLL's is what brought the unification of the IBLA.

In addition, the winner of each RBLL region each season, is granted the prestigious spot to compete in the IBLA Nationals. They play against the winner of each region within the IBLA network across the country.