John Marshall High School (JMHS) is a free public secondary school in the San Antonio suburb of Leon Valley in northwest Bexar County named after Chief Justice John Marshall. The school serves students in grades 9-12, and is part of the Northside Independent School District, with admission based primarily on the locations of students' homes. The campus serves most of the suburb of Leon Valley and large portions of northwest San Antonio. Marshall was named a National Blue Ribbon School in 1992-93.

Northside Independent School District is a school district headquartered in Leon Valley, Texas. It is the largest school district in the San Antonio area and the fourth largest in the State of Texas. Northside serves 355 square miles (920 km2) of urban landscape, suburban growth and rural territory in the San Antonio suburbs and the Hill Country. Northside is roughly 50 percent built out with the center of the district's boundaries near Helotes, just north of the Bandera Road and Loop 1604 intersection. Because of fast-paced growth, the district envisions possibly another four high schools over the next few decades, including far west areas off Potranco Road and Hwy 211, Culebra Road past Talley Road, I-10 near Boerne Stage Road and far north Bandera Road near the Pipe Creek/Bandera County/Medina County areas.