Enrollment
343
Connecticut · 2024-25 NCES data
Elementary school (grades K-5) · Cos Cob, CT
Cos Cob School
Federal NCES profile for Cos Cob School, including enrollment, faculty, free-lunch eligibility, demographics, and resource indicators - Resource Investment Index 60/100.
2024-25 NCES dataElementary school (grades K-5)NCES 090171000296
👥 S:T ratio 63
🌟 Gifted program 70
🎓 Counselors 31
📋 Attendance 75
Scored 0–100 from federal NCES and CRDC indicators, resource allocation, not test scores. Full methodology →
The verdict
Cos Cob School earns 60/100 on the Resource Investment Index, with class sizes smaller than 87% of Connecticut schools.
- 60
- Resource Index · Higher
- 9.3:1
- small classes for Connecticut
- 11.6%
- free-lunch eligible
- 343
- students enrolled
Cos Cob School has class sizes smaller than 87% of Connecticut schools. Computed live against every Connecticut school reporting to NCES.
School address
District: Greenwich School District · Connecticut
NCES ID 090171000296 Verify on NCES CCD record →
Teachers (FTE)
37.0
Federal CCD staff survey
Students per teacher
9.3:1
vs 12.1:1 Connecticut avg
-23% vs state
Free-lunch eligible
11.6%
vs 36.4% Connecticut avg
-68% vs state
Student-teacher ratio in context
How Cos Cob School compares with Connecticut and U.S. medians
What stands out at Cos Cob School
Cos Cob School is a lower-poverty, mid-sized elementary school in Cos Cob, Connecticut, enrolling 343 students.
Classes run notably small here: at 9.3:1, Cos Cob School is leaner than roughly 87% of Connecticut schools and 23% under the state's 12.1:1 norm, more adult attention per pupil than most peers.
Economic need runs somewhat below the state's typical profile, with 11.6% of students eligible for free meals.
With 343 students, its enrollment sits close to the Connecticut median campus size.
Its Resource Investment Index lands in the upper third of 1,003 scored Connecticut schools.
Against 252 statewide peers matched on enrollment and economic need, it ranks in the upper tier at #74.
Its student body is led by White (67%) and Hispanic or Latino (20%) (diversity index 50/100).
Counselor availability sits well past the ASCA benchmark, roughly 343 students sharing each counselor, though short of the most stretched campuses.
10.2% of students were chronically absent in the 2021-22 collection, in line with the post-pandemic national range.
The surrounding Greenwich School District spends $30,449 per pupil, 28% above the Connecticut average, a better-resourced district than most.
Greenwich School District also operates Greenwich High School (2,620 students) and Eastern Middle School (797 students) alongside Cos Cob 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 Cos Cob School compares
Cos Cob School on the metrics families compare, against Connecticut and U.S. means.
| Metric | This school | vs Connecticut | Connecticut avg | U.S. avg |
|---|---|---|---|---|
| Students per teacher | 9.3:1 | ▼ 23% | 12.1:1 | 15.7:1 |
| Free-lunch eligible | 11.6% | ▼ 68% | 36.4% | 51.7% |
| Enrollment | 343 | top 65% | - | - |
Source: NCES Common Core of Data School-level CCD + state/national means from Public School Universe · 2024-25
9.3:1
Leaner classes than 92% of US schools, among the more generously staffed nationally.
343
Bigger than 39% of US schools by enrollment, mid-sized for the country.
Equity indicators (what these measure)
Economic need
11.6%
free-lunch eligible
- 68% below the Connecticut average of 36.4%
Below the 40% Title I threshold, among the lower-need profiles in the state; federal aid targets individual qualifying students rather than schoolwide programs.
Staffing depth
9.3:1
students per teacher
- 23% below state mean
Top 13% in Connecticut - lower ratio than 87% of state schools
Well under the widely cited 15:1 individualized-attention benchmark, among the leaner class loads nationally.
Engagement
10.2%
chronically absent (missed 10%+ of school days)
In the 10-15% range, above the pre-pandemic national baseline but within the broader post-pandemic picture.
Funding equity
$30,449
per pupil, district-wide
- above Connecticut avg of $23,870
Well above the U.S. public-school average, reflecting substantially higher local or state investment per enrolled student.
Support staff
Counselors1.0 FTE
Per 343 students, the combined health-and-guidance staffing load for this school.
Discipline context
0
in-school suspensions + 0 out-of-school
Suspension rate: 0.0 per 100 students. Combined in-school and out-of-school rate: 0.0 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 67.3%
Hispanic or Latino 20.4%
Asian 5.2%
Two or More 5.2%
African American 1.2%
American Indian / Alaska Native 0.6%
Largest group: White at 67.3% of enrollment.
Student-body diversity index 50.0/100
Simpson diversity index - at 50.0, Cos Cob School is about as mixed as the Connecticut school average of 50.5.
Programs
Gifted & talented Yes
Funding & spending
District-wide per-pupil expenditure for Greenwich School District, which includes Cos Cob School.
$30,449
Per student
+28%
vs Connecticut
Avg $23,870
+84%
vs U.S.
Avg $16,593
Revenue mix
Local 81.4%
State 13.5%
Federal 5.1%
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 Cos Cob School Compares to District-Mates
| School | Enrollment | Economic Profile | Student-Teacher Ratio |
|---|---|---|---|
| Greenwich High School | Larger | Similar economic need | Higher S:T ratio |
| Eastern Middle School | Larger | Similar economic need | Similar S:T ratio |
| Western Middle School | Larger | Higher economic need | Similar S:T ratio |
| Central Middle School | Larger | Similar economic need | Similar S:T ratio |
| Riverside School | Larger | Similar economic need | Higher S:T ratio |
Comparisons are relative to Cos Cob School's own figures; each column derives from NCES Common Core of Data.
Other Schools in This District
- Enrollment
- 2,620
- Students per teacher
- 12.5:1
- Resource Index
- 54/100
- Enrollment
- 797
- Students per teacher
- 10.4:1
- Resource Index
- 66/100
- Enrollment
- 563
- Students per teacher
- 8.3:1
- Resource Index
- 67/100
- Enrollment
- 483
- Students per teacher
- 8.8:1
- Resource Index
- 65/100
- Enrollment
- 440
- Students per teacher
- 12.6:1
- Resource Index
- 68/100
Similar elementary schools statewide
Matched by enrollment size and by staffing ratio across all of Connecticut, not just this city - a different peer set than the local comparisons above.
Similar enrollment (~343 students)
Similar student-teacher ratio (~9.3:1)
Next steps
Verify locally before acting on Cos Cob School's federal record.
- Compare Cos Cob School against another school. Compare schools
- Greenwich School District'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 Cos Cob School
How many students attend Cos Cob School?
Cos Cob School has 343 students enrolled. It is an elementary school in Cos Cob, CT.
What is the student-teacher ratio at Cos Cob School?
The student-teacher ratio at Cos Cob School is 9.3:1, which is 23% lower than the Connecticut average of 12.1:1 and 41% lower than the national average of 15.7:1. Lower ratios generally mean more individual attention per student.
What percentage of students receive free lunch at Cos Cob School?
11.6% of students at Cos Cob School are eligible for free lunch, compared to the Connecticut average of 36.4%.
What is the racial and ethnic makeup of Cos Cob School?
The largest demographic group at Cos Cob School is White at 67.3% of enrollment, in Cos Cob, CT. Its student body is more racially and ethnically mixed than most US schools, with a diversity index of 50.0/100.
What is the Resource Investment Index for Cos Cob School?
Cos Cob School has a Resource Investment Index of 60/100 (higher reported resources relative to schools nationally) based on 4 factors: student-teacher ratio, counselor availability, attendance rates. Not a test-score or academic measure (national median ~41/100, see methodology).
Is Cos Cob School a good school?
Cos Cob School earns 60/100 on the Resource Investment Index, with class sizes smaller than 87% of Connecticut schools. 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 Greenwich School District?
Besides Cos Cob School, Greenwich School District also operates Greenwich High School (2,620 students), Eastern Middle School (797 students), and Western Middle School (563 students). See the Greenwich School District 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.