Enrollment
1,279
Illinois · 2024-25 NCES data
High school (grades 9-12) · Crystal Lake, IL
Crystal Lake South High School
Federal NCES profile for Crystal Lake South High School, including enrollment, faculty, free-lunch eligibility, demographics, and resource indicators - Resource Investment Index 51/100.
2024-25 NCES dataHigh school (grades 9-12)NCES 171137001368
👥 S:T ratio 30
📚 AP courses 100
🌟 Gifted program 30
🎓 Counselors 49
📋 Attendance 47
Scored 0–100 from federal NCES and CRDC indicators, resource allocation, not test scores. Full methodology →
The verdict
Crystal Lake South High School earns 51/100 on the Resource Investment Index, with class sizes larger than 89% of Illinois schools. It is also one of the largest schools in Illinois.
- #2 of 3
- high schools in Crystal Lake · Resource Index
- 51
- Resource Index · Higher
- 17.5:1
- large classes for Illinois
- 1,279
- students enrolled
Crystal Lake South High School has class sizes larger than 89% of Illinois schools. Computed live against every Illinois school reporting to NCES.
By Resource Investment Index, Crystal Lake South High School ranks #2 of 3 high schools in Crystal Lake, IL.
School address
NCES ID 171137001368 Verify on NCES CCD record →
Teachers (FTE)
73.0
Federal CCD staff survey
Students per teacher
17.5:1
vs 14:1 Illinois avg
+25% vs state
Student-teacher ratio in context
How Crystal Lake South High School compares with Illinois and U.S. medians
What stands out at Crystal Lake South High School
Crystal Lake South High School is a large high school in Crystal Lake, Illinois, enrolling 1,279 students.
Class loads run heavy: 17.5:1 is larger than about 89% of Illinois schools and 25% above the 14:1 state mean, so each teacher carries more students than is typical.
By headcount it is one of the larger campuses in Illinois, bigger than 95% of state schools at 1,279 students.
Its Resource Investment Index sits near the middle of the pack among 3,845 scored Illinois schools.
Its student body is led by White (65%) and Hispanic or Latino (26%) (diversity index 51/100).
On the academic-pipeline side it reports 20 Advanced Placement courses.
Counselor coverage runs a bit thin, about 256 students per counselor, somewhat past the ASCA-recommended 250:1 benchmark.
Attendance runs somewhat below the norm, with 21.3% of students chronically absent per the 2021-22 civil-rights collection.
The surrounding Chsd 155 spends $22,088 per pupil, 30% above the Illinois average, a better-resourced district than most.
Among Crystal Lake's high schools, it stands alongside Crystal Lake Central High School (1,443 students): Crystal Lake South High School is smaller than that campus by headcount and runs heavier classes (17.5:1 vs 16.6:1).
Chsd 155 also operates Crystal Lake Central High School (1,443 students) and Cary-Grove Community High School (1,348 students) alongside Crystal Lake South High School.
Sourced from NCES CCD, CRDC, and F-33 (federal records, not a quality verdict). How we source and compute this.
Source: National Center for Education Statistics Common Core of Data + CRDC + F-33 · 2024-25
How Crystal Lake South High School compares
Crystal Lake South High School on the metrics families compare, against Illinois and U.S. means.
| Metric | This school | vs Illinois | Illinois avg | U.S. avg |
|---|---|---|---|---|
| Students per teacher | 17.5:1 | ▲ 25% | 14:1 | 15.7:1 |
| Enrollment | 1,279 | top 5% | - | - |
Source: NCES Common Core of Data School-level CCD + state/national means from Public School Universe · 2024-25
17.5:1
Leaner classes than 27% of US schools, heavier class loads than most.
1,279
Bigger than 95% of US schools by enrollment, a large campus nationally.
Equity indicators (what these measure)
Staffing depth
17.5:1
students per teacher
- 25% above state mean
Top 89% in Illinois - lower ratio than 11% of state schools
Between 16:1 and 20:1, squarely in the typical U.S. public-school staffing range.
Engagement
21.3%
chronically absent (missed 10%+ of school days)
At or above 20%, the commonly used threshold for "high" chronic absenteeism, signaling significant barriers to regular attendance.
Funding equity
$22,088
per pupil, district-wide
- above Illinois avg of $17,042
Well above the U.S. public-school average, reflecting substantially higher local or state investment per enrolled student.
Support staff
Counselors5.0 FTE
Per 256 students, the combined health-and-guidance staffing load for this school.
Discipline context
122
in-school suspensions + 56 out-of-school
Suspension rate: 9.5 per 100 students. Combined in-school and out-of-school rate: 13.9 per 100 students. Reported via the Civil Rights Data Collection.
Overview
- Common Core of Data (June 2026): enrollment, staffing, and the student-teacher ratio above.
- Civil Rights Data Collection: discipline counts and program access (AP, gifted, special education).
- F-33 School District Finance Survey: the district-wide per-pupil spending figures below.
Three separate federal collections, each on its own reporting cadence - which is why this school's numbers line up on a consistent basis against every other school and state on this site, rather than mixing figures pulled from different survey years.
Student demographics
White 64.9%
Hispanic or Latino 25.7%
Asian 4.3%
African American 2.7%
Two or More 2.0%
American Indian / Alaska Native 0.3%
Largest group: White at 64.9% of enrollment.
Student-body diversity index 51.0/100
Simpson diversity index - at 51.0, Crystal Lake South High School is more mixed than the Illinois school average of 38.9.
Programs
AP courses offered 20
Funding & spending
District-wide per-pupil expenditure for Chsd 155, which includes Crystal Lake South High School.
$22,088
Per student
+30%
vs Illinois
Avg $17,042
+33%
vs U.S.
Avg $16,593
Revenue mix
Local 62.5%
State 31.9%
Federal 5.6%
Source: NCES F-33 School District Finance Survey District-level finance · FY 2021-22 Per-pupil expenditure reflects the district-wide average. Individual school budgets are not reported at the federal level.
How Crystal Lake South High School Compares to District-Mates
| School | Enrollment | Economic Profile | Student-Teacher Ratio |
|---|---|---|---|
| Crystal Lake Central High School | Similar size | No free-lunch data | Similar S:T ratio |
| Cary-Grove Community High School | Similar size | No free-lunch data | Similar S:T ratio |
| Prairie Ridge High School | Similar size | No free-lunch data | Lower S:T ratio |
Comparisons are relative to Crystal Lake South High School's own figures; each column derives from NCES Common Core of Data.
Other Schools in This District
- Enrollment
- 1,443
- Students per teacher
- 16.6:1
- Resource Index
- 34/100
- Enrollment
- 1,348
- Students per teacher
- 16.2:1
- Resource Index
- 41/100
- Enrollment
- 1,133
- Students per teacher
- 16:1
- Resource Index
- 42/100
Similar high schools in Crystal Lake
2 comparable high schools (grades 9-12) serving the same city.
Similar high schools statewide
Matched by enrollment size and by staffing ratio across all of Illinois, not just this city - a different peer set than the local comparisons above.
Similar enrollment (~1,279 students)
Similar student-teacher ratio (~17.5:1)
Next steps
Verify locally before acting on Crystal Lake South High School's federal record.
- Compare Crystal Lake South High School against another school. Compare schools
- Chsd 155's spending and staffing shape this school. District profile
- Confirm current enrollment and boundaries with the school. Choosing guide
Federal record (CCD 2024-25, CRDC 2021-22) - PlainSchools assigns no subjective rating; the composite quality score is a transparent, reproducible index computed from this cited federal data.
Frequently asked questions about Crystal Lake South High School
How many students attend Crystal Lake South High School?
Crystal Lake South High School has 1,279 students enrolled. It is a high school in Crystal Lake, IL.
What is the student-teacher ratio at Crystal Lake South High School?
The student-teacher ratio at Crystal Lake South High School is 17.5:1, which is 25% higher than the Illinois average of 14:1 and 11% higher than the national average of 15.7:1.
What is the racial and ethnic makeup of Crystal Lake South High School?
The largest demographic group at Crystal Lake South High School is White at 64.9% of enrollment, in Crystal Lake, IL. Its student body is more racially and ethnically mixed than most US schools, with a diversity index of 51.0/100.
What is the Resource Investment Index for Crystal Lake South High School?
Crystal Lake South High School has a Resource Investment Index of 51/100 (higher reported resources relative to schools nationally) based on 5 factors: student-teacher ratio, AP course offerings, counselor availability, attendance rates. Not a test-score or academic measure (national median ~41/100, see methodology).
How does Crystal Lake South High School rank among high schools in Crystal Lake?
By Resource Investment Index, Crystal Lake South High School ranks #2 of 3 high schools in Crystal Lake, IL. This compares federal resource and staffing data among local peers; it is not a test-score or academic ranking. See all high schools in Crystal Lake on the city page.
Is Crystal Lake South High School a good school?
Crystal Lake South High School earns 51/100 on the Resource Investment Index, with class sizes larger than 89% of Illinois schools. It is also one of the largest schools in Illinois. This is a resource snapshot, not an academic rating; see the Resource Investment Index question above for what the number does and doesn't measure.
What other schools are in Chsd 155?
Besides Crystal Lake South High School, Chsd 155 also operates Crystal Lake Central High School (1,443 students), Cary-Grove Community High School (1,348 students), and Prairie Ridge High School (1,133 students). See the Chsd 155 district page for the complete list.
Related tools
Every figure on PlainSchools is rendered directly from the source NCES, CRDC and F-33 federal records, no number is typed in by an editor. Each school's figures reflect its most recent NCES/CRDC submission on file. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of June 2026.