| Index | Greencastle | Pennsylvania | National |
| Average Test Scores | 69% | 55% | 48% |
| Student/Teacher ratio | 19:1 | 16:1 | 16:1 |
| Total public schools | 4 | 2,563 | 79,221 |
| Total private schools | 2 | 1,626 | 24,874 |
| Total post-secondary schools | n/a | 406 | 7,963 |
| Index | Greencastle | Pennsylvania | National |
| Completed 8th grade | 88.2% | 86.9% | 84.3% |
| Completed high school | 85.4% | 85.6% | 83.0% |
| Completed some college | 49.7% | 53.6% | 59.4% |
| Completed associate degree | 31.5% | 37.4% | 38.5% |
| Completed bachelors | 25.7% | 29.3% | 30.3% |
| Completed masters | 11.4% | 11.5% | 11.5% |
| Completed professional degree | 3.9% | 3.3% | 3.3% |
| Completed doctorate | 0.6% | 1.4% | 1.3% |
There are a total of 4 public schools, 2 private schools and n/a post-secondary schools in Greencastle. Using the proficiency score averages, the average test scores for Greencastle, PA schools is 69%. The average student to teacher ratio is 19:1. In Greencastle, PA, an average of 88.2% of students have completed 8th grade and an average of 85.4% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Sabillasville, MD | 390 | 65% | 35.4% |
| Fayetteville, PA | 2,855 | 64% | 32.3% |
| McConnellsburg, PA | 1,030 | 63% | 31.6% |
| Mercersburg, PA | 1,673 | 62% | 29.0% |
| Waynesboro, PA | 10,898 | 61% | 27.8% |
| Greencastle, PA | 4,008 | 69% | 44.4% |
| City | Population | Avg. Test Scores | National Avg. |
| Esparto, CA | 4,009 | 27% | 44.1% |
| Clay Center, KS | 4,007 | 44% | 8.6% |
| Centerville, MN | 4,006 | 82% | 70.8% |
| Akron, PA | 4,006 | 65% | 34.4% |
| Fredericktown, MO | 4,006 | 42% | 12.5% |
| Greencastle, PA | 4,008 | 69% | 44.4% |
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