The Great Lakes Athletic Conference is a four-member IHSAA-sanctioned conference located entirely within Lake County. The conference is among the youngest in the state, created in 2007 following the disbandment of the Lake Athletic Conference and after failing to find acceptance in another conference for each of the four schools. The GLAC's "sister" conferences also created from the Lake Athletic Conference are the Greater South Shore Athletic Conference and the Northwest Crossroads Conference. At the start of the 2021–2022 school year, the conference lost two members as Hammond Clark and Hammond Gavit were closed due to the consolidation of Hammond Schools.
| School | Town | Team Name | Colors | Enrollment https://www.ihsaa.org/sites/default/files/documents/Boys%20Basketball%20Classifications%20for%202024-25%20and%202025-26.pdf 24-25 | IHSAA Class | IHSAA Class Football | Year joined | Previous conference | |
|---|---|---|---|---|---|---|---|---|---|
| East Chicago Central | East Chicago, Indiana | Cardinals | 1009 | 3A | 4A | 2016 | Independents (ILSC 1987) | ||
| Gary West Side | Gary, Indiana | Cougars | 995 | 3A | 4A | 2018 | Independents (NWC 2014) | ||
| Hammond Central | Hammond, Indiana | Wildcats | 1923 | 4A | 5A | 2007 | Lake | ||
| Hammond Morton | Hammond, Indiana | Governors | 1534 | 4A | 5A | 2007 | Lake |