| Index | Old Mystic | Connecticut | National |
| Average Test Scores | n/a | 53% | 48% |
| Student/Teacher ratio | 20:1 | 14:1 | 16:1 |
| Total public schools | 2 | 654 | 79,221 |
| Total private schools | n/a | 207 | 24,874 |
| Total post-secondary schools | n/a | 81 | 7,963 |
| Index | Old Mystic | Connecticut | National |
| Completed 8th grade | 92.4% | 88.0% | 84.3% |
| Completed high school | 91.2% | 86.9% | 83.0% |
| Completed some college | 69.7% | 62.9% | 59.4% |
| Completed associate degree | 54.2% | 45.5% | 38.5% |
| Completed bachelors | 43.8% | 38.0% | 30.3% |
| Completed masters | 21.3% | 16.8% | 11.5% |
| Completed professional degree | 3.3% | 4.6% | 3.3% |
| Completed doctorate | 2.7% | 1.7% | 1.3% |
There are a total of 2 public schools, n/a private schools and n/a post-secondary schools in Old Mystic. Using the proficiency score averages, the average test scores for Old Mystic, CT schools is n/a. The average student to teacher ratio is 20:1. In Old Mystic, CT, an average of 92.4% of students have completed 8th grade and an average of 91.2% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Fishers Island, NY | 61 | 80% | 66.7% |
| Stonington, CT | 899 | 77% | 60.4% |
| Niantic, CT | 3,083 | 77% | 59.4% |
| Ashaway, RI | 1,444 | 72% | 50.0% |
| Pawcatuck, CT | 5,024 | 68% | 42.4% |
| Old Mystic, CT | 3,302 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Mobridge, SD | 3,303 | 57% | 19.1% |
| Southampton, NY | 3,301 | 48% | 0.8% |
| Lakeland, GA | 3,303 | 38% | 20.1% |
| Water Valley, MS | 3,300 | 36% | 26.0% |
| Hartford, SD | 3,300 | 47% | 1.6% |
| Old Mystic, CT | 3,302 | n/a |
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