| Franciscan Montessori Earth School | Portland | PreK-8 | 228 | 15.6 | Roman Catholic |
| Childpeace Montessori School | Portland | PreK-8 | 186 | 7.8 | Nonsectarian |
| Maple Corner Montessori | Roseburg | PreK-8 | 141 | 8.6 | Nonsectarian |
| West Hills Montessori School-Vermont | Portland | PreK-6 | 103 | 5.2 | Nonsectarian |
| Angels Academy | Beaverton | K-2 | 94 | 8.5 | Nonsectarian |
| Medford Montessori School | Medford | PreK-5 | 89 | 6 | Nonsectarian |
| Sunstone Montessori School | Portland | PreK-6 | 85 | 12.1 | Nonsectarian |
| Puddletown School | Portland | PreK-8 | 66 | 9.4 | Nonsectarian |
| The Portland Montessori School | Portland | PreK-4 | 55 | 9.2 | Nonsectarian |
| Little Friends Montessori School | Salem | PreK-5 | 34 | 5.9 | Nonsectarian |
| McMinnville Montessori School | McMinnville | PreK-6 | 33 | 8.2 | Nonsectarian |
| McKenzie Montessori | Springfield | PreK-3 | 25 | 5.8 | Nonsectarian |
| Morningstar Montessori House of Children | Gresham | K-Transitional K | 20 | 6.7 | Nonsectarian |
| West Hills Montessori School-Lake Oswego | Lake Oswego | PreK-K | 17 | 2 | Nonsectarian |
| Monmouth Montessori School | Monmouth | PreK-2 | 15 | 7.5 | Nonsectarian |
| Crescent Islamic Montessori School | Beaverton | PreK-2 | 15 | 5.8 | Islamic, all-girls |
| Hillsview Montessori School | Gresham | PreK-1 | 14 | 14 | Christian (nondenominational) |
| Sunnyside Mennonite Montessori School | Portland | K | 11 | 5.5 | Nonsectarian |
| Oregon Hope Chinese School | Portland | PreK-Transitional K | 10 | 2 | Nonsectarian |
| Whole Child Montessori Center | Portland | PreK-K | 10 | 2.3 | Nonsectarian |
| Corvallis Montessori School | Corvallis | PreK-K | 10 | 3.3 | Nonsectarian |
| Sundborn Childrens House, A Montessori School | Albany | PreK-K | 8 | 4 | Nonsectarian |
| Sunnyside Montessori House of Children | Happy Valley | PreK-K | 8 | 4 | Christian (nondenominational) |
| Eugene Montessori School | Eugene | PreK-K | 7 | 2.1 | Nonsectarian |
| Harmony Montessori School | Portland | PreK-K | 7 | not reported | Nonsectarian |
| Forest Grove Montessori | Forest Grove | PreK-K | 5 | 5 | Nonsectarian |
| Busy Hands Montessori | Portland | PreK-K | 5 | not reported | Nonsectarian |
| Montessori of Alameda | Portland | PreK-K | 4 | not reported | Nonsectarian |
| Philomath Montessori School | Philomath | PreK-K | 4 | 3.1 | Nonsectarian |
| Chestnut Grove Montessori Childrens House | Portland | PreK-K | 3 | 3 | Nonsectarian |
| Children's Choice Montessori School-Springfield | Eugene | PreK-K | 3 | 3 | Nonsectarian |
| Portland Montessori Collaborative | Portland | PreK-K | 2 | 2 | Nonsectarian |
| Montessori Childrens House | Portland | PreK-K | 2 | not reported | Nonsectarian |
| Smockville Montessori School | Sherwood | PreK-K | 1 | not reported | Nonsectarian |
| Parkrose Montessori | Portland | PreK-K | 1 | not reported | Nonsectarian |
| Woodlawn Montessori | Portland | PreK-K | 1 | not reported | Nonsectarian |