| Seven Hills At Groton | 3.3 |
Special education | 1-12 | 25 | 8.3 | Nonsectarian |
| Mary Mcleod Bethune Institute | 3.9 |
Special program emphasis | 3-12 | 45 | 8.0 | Nonsectarian |
| Nashoba Learning Group | 7.5 |
Special education | Pre-KG-11 | 40 | 0.8 | Nonsectarian |
| Seven Hills Academy | 8.6 |
Special education | 4-12 | 60 | 14.6 | Nonsectarian |
| Lighthouse School | 10.0 |
Special education | Pre-KG-12 | 220 | 6.7 | Nonsectarian |
| Twin City Christian School | 10.0 |
Regular elementary or secondary | Pre-KG-12 | 191 | 12.2 | Baptist |
| Riverside School | 12.2 |
Special education | 2-12 | 34 | 4.9 | Nonsectarian |
| Applewild School | 12.3 |
Regular elementary or secondary | KG-9 | 282 | 7.8 | Nonsectarian |
| Merrimack Schools | 13.7 |
Alternative/other | 5-12 | 55 | 2.5 | Nonsectarian |
| Rfk Lancaster School | 15.6 |
Special education | 4-12 | 36 | 1.1 | Nonsectarian |
| South Lancaster Academy And Browning Elementary | 15.7 |
Regular elementary or secondary | Pre-KG-12 | 237 | 15.0 | Seventh-Day Adventist |
| Sterling Nursery School | 17.1 |
Special education | Pre-KG-Pre-KG | 3 | 0.8 | Nonsectarian |
| Melmark New England | 17.3 |
Special education | Ungraded-Ungraded | 108 | 1.5 | Nonsectarian |
| The Fenn School | 17.5 |
Regular elementary or secondary | 4-9 | 304 | 8.2 | Nonsectarian |
| Fellowship Christian Academy | 19.2 |
Regular elementary or secondary | Pre-KG-12 | 108 | 10.8 | Christian (no specific denomination) |
| Willow Hill School | 19.3 |
Special education | 6-12 | 60 | 3.4 | Nonsectarian |
| St Ann's Home Inc | 20.0 |
Special education | Ungraded-Ungraded | 122 | 6.7 | Nonsectarian |
| Hillside School | 21.4 |
Regular elementary or secondary | 5-9 | 139 | 6.0 | Nonsectarian |
| The Pike School | 22.9 |
Regular elementary or secondary | Pre-KG-9 | 418 | 9.1 | Nonsectarian |
| Community Therapeutic Day School Inc | 23.7 |
Special education | Ungraded-Ungraded | 30 | 2.6 | Nonsectarian |
| Sudbury Valley School | 24.1 |
Special program emphasis | Ungraded-Ungraded | 165 | 16.7 | Nonsectarian |
| Reed Academy | 24.1 |
Special education | Ungraded-Ungraded | 20 | 3.4 | Nonsectarian |
| Open Bible Academy | 24.1 |
Regular elementary or secondary | Pre-KG-12 | 71 | 6.2 | Christian (no specific denomination) |
| Cotting School | 24.3 |
Special education | Ungraded-Ungraded | 119 | 4.8 | Nonsectarian |
| Cottage Hill Academy | 24.5 |
Special education | 6-12 | 32 | 4.0 | Nonsectarian |
| Fay School | 24.7 |
Regular elementary or secondary | 1-9 | 379 | 6.6 | Nonsectarian |
| Bradford Christian Academy | 25.0 |
Regular elementary or secondary | 6-12 | 65 | 7.4 | Christian (no specific denomination) |
