The Sac-Joaquin Section (SJS) is the governing body of public and private high school athletics in parts of the Northern San Joaquin Valley, California.

Its geographic area also covers the California portion of the Lake Tahoe region; however, three schools in that area—North Tahoe, Truckee, and South Tahoe High Schools—are instead members of the Nevada Interscholastic Activities Association due to their relative isolation from other California schools and their proximity to more populated areas in Nevada, especially in the Reno area.

It is one of ten sections that compose the California Interscholastic Federation (CIF).

The SJS is split into seven divisions, each comprising several leagues.

[1] The section is governed by a board of managers, whose voting members include representatives from member leagues, superintendents, school board associations and private schools.