The International School of the Americas (ISA) is a magnet school for grades 9-12 in the North East Independent School District in San Antonio, Texas in Bexar County. It is located on the Lee High School campus at 1400 Jackson-Keller Road. Admission is by lottery. The school is notable for its intentionally small student body and for its Model United Nations conference, named Model United Nations San Antonio (MUNSA), which is the largest such student-run conference in the nation.