#1 Largest Private Schools in Middlesex County, MA
Malden Catholic High School
Independent Catholic school · Grades 9–12
863 students
Malden, MA
A+Overall grade863 students12 students per teacher
2026 lists
Largest Private Schools in Middlesex County, MA
The private schools in Middlesex County, MA with the most students. Top 50 of 105 schools.
#2 Largest Private Schools in Middlesex County, MA
Arlington Catholic High School/Saint Agnes School
Diocesan school · Grades Pre-K–12
851 students
Arlington, MA
A-Overall grade851 students10 students per teacher
#3 Largest Private Schools in Middlesex County, MA
Austin Preparatory School
Independent Catholic school · Grades 6–12
806 students
Reading, MA
B+Overall grade806 students11 students per teacher
#4 Largest Private Schools in Middlesex County, MA
Lowell Catholic
Diocesan school · Grades Pre-K–12
705 students
Lowell, MA
B-Overall grade705 students11 students per teacher
#5 Largest Private Schools in Middlesex County, MA
The Rivers School
Independent school · Grades 6–12
525 students
Weston, MA
A+Overall grade525 students6 students per teacher
#6 Largest Private Schools in Middlesex County, MA
Academy of Notre Dame
Diocesan school · Grades Pre-K–12
502 students
Tyngsboro, MA
A-Overall grade502 students11 students per teacher
#7 Largest Private Schools in Middlesex County, MA
Shady Hill School
Independent school · Grades Pre-K–8
496 students
Cambridge, MA
A-Overall grade496 students7 students per teacher
#8 Largest Private Schools in Middlesex County, MA
The Carroll School
Special education school · Grades 1–9
455 students
Lincoln, MA
A+Overall grade455 students3 students per teacher
#9 Largest Private Schools in Middlesex County, MA
Lawrence Academy
Independent school · Grades 9–12
415 students
Groton, MA
A-Overall grade415 students7 students per teacher
#10 Largest Private Schools in Middlesex County, MA
Brimmer & May School
Independent school · Grades Pre-K–12
394 students
Chestnut Hill, MA
A+Overall grade394 students6 students per teacher
#11 Largest Private Schools in Middlesex County, MA
Groton School
Episcopal school · Grades 8–12
381 students
Groton, MA
A+Overall grade381 students6 students per teacher
#12 Largest Private Schools in Middlesex County, MA
Newton Country Day School
Independent Catholic school · Grades 5–12
374 students
Newton, MA
A+Overall gradeAll girls374 students5 students per teacher
#13 Largest Private Schools in Middlesex County, MA
Solomon Schechtee Day School
Jewish day school · Grades Pre-K–8
359 students
Newton, MA
A-Overall grade359 students4 students per teacher
#14 Largest Private Schools in Middlesex County, MA
Solomon Schechter Day School
Jewish day school · Grades Pre-K–8
359 students
Newton, MA
B-Overall grade359 students6 students per teacher
#15 Largest Private Schools in Middlesex County, MA
Gann Academy-The New Jewish High School
Jewish day school · Grades 9–12
351 students
Waltham, MA
AOverall grade351 students7 students per teacher
#16 Largest Private Schools in Middlesex County, MA
Belmont Day School
Independent school · Grade 1
334 students
Belmont, MA
A+Overall grade334 students4 students per teacher
#17 Largest Private Schools in Middlesex County, MA
Our Ladys Academy
Parish school · Grades Pre-K–8
328 students
Waltham, MA
A+Overall grade328 students8 students per teacher
#18 Largest Private Schools in Middlesex County, MA
The Fenn School
Independent school · Grades 4–9
310 students
Concord, MA
BOverall gradeAll boys310 students7 students per teacher
#19 Largest Private Schools in Middlesex County, MA
The Cambridge School of Weston
Independent school · Grades 9–12
307 students
Weston, MA
A+Overall grade307 students7 students per teacher
#20 Largest Private Schools in Middlesex County, MA
Immaculate Conception School
Parish school · Grades Pre-K–8
303 students
Lowell, MA
BOverall grade303 students15 students per teacher
#21 Largest Private Schools in Middlesex County, MA
Meadowbrook School of Weston
Independent school · Grades Pre-K–8
295 students
Weston, MA
A+Overall grade295 students5 students per teacher
#22 Largest Private Schools in Middlesex County, MA
St. Agnes School
Diocesan school · Grades Pre-K–8
291 students
Arlington, MA
A+Overall grade291 students10 students per teacher
#23 Largest Private Schools in Middlesex County, MA
Lexington Christian Academy
Christian school (nondenominational) · Grades 6–12
290 students
Lexington, MA
A+Overall grade290 students9 students per teacher
#24 Largest Private Schools in Middlesex County, MA
Cheverus Catholic School
Parish school · Grades Pre-K–8
289 students
Malden, MA
A+Overall grade289 students12 students per teacher
From official public records, updated October 2026.