Cos Cob School vs Old Greenwich School
A head-to-head comparison of two elementary schools in Connecticut, United States, 2.8 km apart, using official American 2025 data. The better value in each row is highlighted.
Cos Cob School
Cos Cob · Public elementary · Grades PK–5
343 students
Old Greenwich School
Old Greenwich · Public elementary · Grades PK–5
385 students
| Measure | Cos Cob School Cos Cob, Connecticut | Old Greenwich School Old Greenwich, Connecticut |
|---|---|---|
| Success Index (US) | 89 Top 5% | 97 Top 5% |
| State rank | #74 of 596 | #5 of 596 |
| National rank | #908 of 50,301 | #31 of 50,301 |
| Sector | Public | Public |
| Type | Elementary | Elementary |
| Year range | Grades PK–5 | Grades PK–5 |
| Students | 343 | 385 |
| Enrollment | 343 | 385 |
| Free/reduced-price lunch | 16% | 2.3% |
| Students per teacher | 10.1 | 10.7 |
| Reading proficiency | 72% | 87% |
| Math proficiency | 74% | 86% |
| city | Cos Cob | Old Greenwich |
| state | Connecticut | Connecticut |
| Website | – | – |
The verdict
- •Old Greenwich School scores higher on the Success Index (US) (96.8 vs 89.4).
- •Old Greenwich School does better on math proficiency (86% vs 74%).
- •Old Greenwich School does better on reading proficiency (87% vs 72%).
- •Old Greenwich School does better on community advantage (fewer free/reduced-price lunch) (2.3% vs 16%).
- •Cos Cob School does better on students per teacher (10.1 vs 10.7).
- •Old Greenwich School is the larger school with 385 students compared with 343.
The Success Index (US) summarises published results and context from official data. It does not measure teaching quality or fit. Methodology.
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Frequently asked questions
Is Cos Cob School better than Old Greenwich School?
On the Success Index (US), Old Greenwich School ranks higher (96.8 vs 89.4 out of 100). The index is built from published results and context data, not from teaching quality or fit, so visit both schools before deciding.
How far apart are Cos Cob School and Old Greenwich School?
About 2.8 km in a straight line, between Cos Cob and Old Greenwich in Connecticut.
Which has the better Enrollment?
Cos Cob School: 343. Old Greenwich School: 385. Students enrolled in the latest NCES directory year.
How do Cos Cob School and Old Greenwich School rank in Connecticut?
Cos Cob School is 74th of 596 and Old Greenwich School is 5th of 596 among elementary schools in Connecticut on the 2025 Success Index (US).