School Information

Crystal Lake South is consistently ranked among the best high public schools in Illinois and offers students a comprehensive 9-12 grade education. Students have the opportunity to choose from more than 200 courses including specialized Advanced Placement®, dual credit, Project Lead the Way (PLTW), and Virtual Enterprises International (VEI).

Crystal Lake South is recognized nationally, and appeared on the Washington Post’s 2017 list of America’s Most Challenging High Schools. The Chicago Sun-Times has listed Crystal Lake South as the 114th best public high school in the state out of 677 schools. Along with the other District 155 schools, Crystal Lake South appeared on the College Board's 2017 AP® District Honor Roll for the sixth consecutive year.

In athletics, the Crystal Lake South Gators compete in the Valley Division of the Fox Valley Conference.  Most recently, the school has captured state titles in boys’ soccer (2018), wrestling (2019), and and baseball (2017). The school has also finished in the state's top four in girls' volleyball five times dating back to 1991.

Crystal Lake South offers students 35 clubs and activities and several opportunities in performing and fine arts. The school’s production of “Peter Pan” was won Best Scenic Design from the Illinois High School Musical Theatre awards in 2018.

Crystal Lake South High School opened in 1978 and serves students from Crystal Lake and Lake in the Hills and located approximately 45 miles north­west of Chicago. The school counts television writer and producer Tom Mularz, season 1 American Idol finalist Jim Varraros among its alumni and former students.

Crystal Lake South 

2017 Washington Post - Most Challenging High School
2017 AP® District Honor Roll

Crystal Lake South: 1,465
District 155: 6,113

CLS Average Class Size: 18
D155 Average Class Size: 18

Teachers with a 
Master's Degree or Higher
: 86%

4-Year Graduation Rate
Crystal Lake South:
District 155: 95%
State: 85%

Scholarships earned in 2017-2018: $3,190,747

Students continuing their education: 93% 

2017-2018 SAT Average
Crystal Lake South ELA: 547.9
Crystal Lake South Math: 555.5

District 155 ELA: 540.1
District 155 Math: 549.9

State ELA: 505.7
State Math: 504.1

2017-18 Advanced Placement® & Dual Credit

AP®Exams Taken
Crystal Lake South:
District 155: 5,514

Number AP® Exams Resulting in College Credit 
Crystal Lake South: 
District 155: 4,286

Dual Credit Courses & Enrollment

Autos II                                      22
     -McHenry County College
Calculus                                     26
     - University of Illinois
Computer Business App.       282
      -McHenry County College
Culinary Arts II Commercial    32
      -McHenry County College
Marketing                                   81
      -McHenry County College
Music Appreciation                   33
      -McHenry County College
Spanish IV                                  289
      -McHenry County College