- Saint Joseph High School
- Salem High School
- Scecina Memorial High School
- Scottsburg Senior High School
- Seeger Memorial Jr-Sr High School
- Seton Catholic High School
- Seymour Christian Academy
- Seymour Senior High School
- Shakamak Jr-Sr High School
- Shawe Memorial High School
- Shelbyville Sr High School
- Shenandoah High School
- Sheridan High School
- Shoals Comm Jr-Sr High School
- Shortridge High School
- Shults-Lewis Child & Family Srvs
- Signature School Inc
- Silver Creek High School
- Smith Academy for Excellence
- South Adams High School
- South Central Jr-Sr High School
- South Central Jr-Sr High School
- South Dearborn High School
- South Decatur Jr-Sr High School
- South Knox Middle-High School
- South Newton Senior High School
- South Putnam High School
- South Ripley High School
- South Side High School
- South Spencer High School
- South Vermillion High School
- Southern Wells Jr-Sr High School
- Southmont Sr High School
- Southport High School
- Southridge High School
- Southwest IN Regional Youth Vlg
- Southwestern High School
- Southwestern High School
- Southwood Jr-Sr High School
- Speedway Senior High School
- Springs Valley Comm High School
- Suburban Christian School
- Sullivan High School
- Switzerland Co Senior High School
- T. C. Harris School
- T.R.O.Y. Center
- Tabernacle Christian School
- Taylor High School
- Tecumseh High School
- Tell City Jr-Sr High School
- Terre Haute North Vigo High School
- Terre Haute South Vigo High School
- The Acad of Sci & Entrepreneurship
- The Crossing Educational Center
- The Excel Center - Anderson
- The Excel Center - Nobelsville
- The Excel Center - University Heights
- The Independence Academy
- The King's Academy
- Thea Bowman Leadership Academy
- Theodore Roosevelt Career & Technical Academy
- Thomas A Edison Jr-Sr High School
- Thomas Carr Howe Community High School
- Tippecanoe Valley High School
- Tipton High School
- Traders Point Christian Academy
- Transitions Academy
- Tri Central Middle-High School
- Tri Junior-Senior High School
- Tri-County Middle-Senior High
- Tri-West Senior High School
- Trinity Christian School
- Trinity Lutheran High School
- Trinity School At Greenlawn
- Triton Central High School
- Triton Jr-Sr High School
- Twin Lakes Senior High School
- Union City Community Jr/Sr HS
- Union County High School
- Union Junior & High School