| Index | Shelter Island | New York | National |
| Average Test Scores | 45% | 56% | 48% |
| Student/Teacher ratio | n/a | n/a | 16:1 |
| Total public schools | 1 | 4,060 | 79,221 |
| Total private schools | n/a | 1,092 | 24,874 |
| Total post-secondary schools | n/a | 483 | 7,963 |
| Index | Shelter Island | New York | National |
| Completed 8th grade | 94.6% | 83.5% | 84.3% |
| Completed high school | 94.6% | 82.1% | 83.0% |
| Completed some college | 71.4% | 59.5% | 59.4% |
| Completed associate degree | 57.9% | 43.4% | 38.5% |
| Completed bachelors | 51.4% | 34.7% | 30.3% |
| Completed masters | 26.9% | 15.1% | 11.5% |
| Completed professional degree | 2.4% | 4.2% | 3.3% |
| Completed doctorate | 1.8% | 1.5% | 1.3% |
There are a total of 1 public schools, n/a private schools and n/a post-secondary schools in Shelter Island. Using the proficiency score averages, the average test scores for Shelter Island, NY schools is 45%. The average student to teacher ratio is n/a. In Shelter Island, NY, an average of 94.6% of students have completed 8th grade and an average of 94.6% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Amagansett, NY | 510 | 80% | 66.7% |
| Fishers Island, NY | 61 | 80% | 66.7% |
| Mattituck, NY | 4,898 | 77% | 60.4% |
| Sag Harbor, NY | 1,959 | 65% | 34.4% |
| East Hampton, NY | 920 | 63% | 31.0% |
| Shelter Island, NY | 1,980 | 45% | 7.3% |
| City | Population | Avg. Test Scores | National Avg. |
| Tavernier, FL | 1,980 | 71% | 47.9% |
| Ocean Park, WA | 1,980 | 35% | 27.1% |
| Hollandale, MS | 1,980 | 23% | 51.6% |
| Cooper, TX | 1,981 | 46% | 3.8% |
| Allegany, NY | 1,981 | 56% | 16.7% |
| Shelter Island, NY | 1,980 | 45% | 7.3% |
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