Illinois Schools
- Shiloh College
- Shiloh School District
- Shimer College
- Siebel Institute Of Technology
- Simeon Career Academy
- Skokie School District 69
- Skokie School District 73½
- Slivka Science & Engineering Residential College
- Solex College
- Sonia Shankman Orthogenic School
- South Elgin High School
- South Holland School District 150
- South Holland School District 151
- South Mid Quads Residence Hall
- South Side Baptist School
- South Side School
- South Suburban College
- Southeastern High School
- Southeastern Illinois College
- Southern Illinois University
- Southern Illinois University Carbondale
- Southern Illinois University Edwardsville
- Southern Illinois University School Of Dental Medicine
- Southern Illinois University School Of Medicine
- Southwestern High School
- Southwestern Illinois College
- Spertus Institute For Jewish Learning And Leadership
- Spoon River College
- Spoon River Valley High School
- Springfield High School
- Springfield School District 186
- Springfield Southeast High School
- Springmore School
- St Anthony High School
- St Augustine College
- St Bede Academy
- St Benedict High School
- St Charles East High School
- St Charles North High School
- St Edward Central Catholic High School
- St Francis High School
- St Francis De Sales High School
- St Gregory Episcopal School
- St Ignatius College Prep
- St John's College
- St Joseph Community Consolidated School District 169
- St Joseph High School
- St Laurence High School
- St Margaret Mary School
- St Mary's School
- St Matthew Evangelical Lutheran School
- St Patrick High School
- St Rita Of Cascia High School
- St Sava Academy
- St Sava's Serbian Orthodox Seminary
- St Teresa High School
- St Thomas Catholic High School For Boys
- St Thomas More High School
- St Viator College
- St Viator High School
- Stark County High School
- State Community College Of East Saint Louis
- Steger School District 194
- Steinmetz College Prep
- Stephen Tyng Mather High School
- Steppenwolf Theatre Company
- Sterling High School
- Stevenson High School
- Stewardson Strasburg High School
- Stockton High School
- Streamwood High School
- Streator Township High School
- Stritch School Of Medicine
- Stuart School Of Business
- Sullivan High School
- Sullivan School District
- Summit School District 104
- Sunnybrook School District 171
- Sunset Ridge School District 29
- Sycamore High School
- Taylorville High School
- Telshe Yeshiva
- Teutopolis High School
- Thayer J Hill Middle School
- The Angel Network
- The Avery Coonley School
- The Chicago School Of Professional Psychology
- The Einstein Academy
- The Henry B Favill School Of Occupations
- The Institute For Clinical Social Work
- The Morrison Shearer Foundation
- The Theatre School At Depaul University
- The Willows Academy
- Theodore Roosevelt High School
- Thomas Elementary School
- Thomas Jefferson High School
- Thomas Kelly High School
- Thompsonville Community Unit School District 174
- Thornridge High School
- Thornton Fractional North High School