MASSA is a district of the Interscholastic Sailing Association, which coordinates secondary school sailing in the U.S. The Midatlantic district includes high school teams in New York, New Jersey, Delaware, Pennsylvania, Maryland, and Virginia. The district is organized into a league-based structure.

There are currently 5 leagues: MDISA, NJISA, NYISA-NW, NYISA-SE and VISA. A school will primarily sail in local regattas arranged by the leagues, who are responsible for selecting teams to attend MASSA District regattas. There will be MASSA Championship regattas each semester and there will be qualifier events to select district representatives to compete in the annual National Championships for single-handed (Cressy), double handed (Mallory), and team racing (three double-handed teams for the Baker).

MASSA has a board of directors which includes the league directors.