| Index | Cos Cob | Connecticut | National |
| Average Test Scores | 73% | 53% | 48% |
| Student/Teacher ratio | n/a | 14:1 | 16:1 |
| Total public schools | n/a | 654 | 79,221 |
| Total private schools | n/a | 207 | 24,874 |
| Total post-secondary schools | n/a | 81 | 7,963 |
| Index | Cos Cob | Connecticut | National |
| Completed 8th grade | 96.5% | 88.0% | 84.3% |
| Completed high school | 96.1% | 86.9% | 83.0% |
| Completed some college | 83.7% | 62.9% | 59.4% |
| Completed associate degree | 73.3% | 45.5% | 38.5% |
| Completed bachelors | 66.5% | 38.0% | 30.3% |
| Completed masters | 34.5% | 16.8% | 11.5% |
| Completed professional degree | 6.3% | 4.6% | 3.3% |
| Completed doctorate | 2.2% | 1.7% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in Cos Cob. Using the proficiency score averages, the average test scores for Cos Cob, CT schools is 73%. The average student to teacher ratio is n/a. In Cos Cob, CT, an average of 96.5% of students have completed 8th grade and an average of 96.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Sea Cliff, NY | 5,045 | 92% | 91.7% |
| Glen Head, NY | 4,843 | 89% | 85.7% |
| Bronxville, NY | 6,450 | 88% | 82.3% |
| Scarsdale, NY | 17,890 | 87% | 81.8% |
| Cold Spring Harbor, NY | 2,864 | 87% | 81.3% |
| Cos Cob, CT | 7,065 | 73% | 52.1% |
| City | Population | Avg. Test Scores | National Avg. |
| Delphos, OH | 7,066 | 82% | 70.1% |
| Hewlett, NY | 7,064 | 82% | 70.5% |
| Hudson Falls, NY | 7,067 | 51% | 5.7% |
| Morrow, GA | 7,061 | 32% | 33.8% |
| Orland Hills, IL | 7,069 | 42% | 13.5% |
| Cos Cob, CT | 7,065 | 73% | 52.1% |
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