#1 Largest Private Schools in San Mateo County, CA
Sacred Heart Schools Atherton
Independent Catholic school · Grades Pre-K–12
1,144 students
Atherton, CA
BOverall grade1,144 students
2026 lists
Largest Private Schools in San Mateo County, CA
The private schools in San Mateo County, CA with the most students. Top 50 of 58 schools.
#2 Largest Private Schools in San Mateo County, CA
Stanford Online High School
Independent school · Grades 7–12
985 students
Redwood City, CA
B+Overall grade985 students15 students per teacher
#3 Largest Private Schools in San Mateo County, CA
The Nueva School
Independent school · Grades Pre-K–12
950 students
San Mateo, CA
A+Overall grade950 students7 students per teacher
#4 Largest Private Schools in San Mateo County, CA
Jserra Catholic High School
Diocesan school · Grades 9–12
863 students
San Mateo, CA
BOverall gradeAll boys863 students17 students per teacher
#5 Largest Private Schools in San Mateo County, CA
Junipero Serra High School
Diocesan school · Grades 9–12
859 students
San Mateo, CA
BOverall gradeAll boys859 students18 students per teacher
#6 Largest Private Schools in San Mateo County, CA
Menlo School
Independent school · Grades 6–12
818 students
Atherton, CA
B-Overall grade818 students9 students per teacher
#7 Largest Private Schools in San Mateo County, CA
St. Matthew Catholic School
Parish school · Grades K–8
625 students
San Mateo, CA
BOverall grade625 students24 students per teacher
#8 Largest Private Schools in San Mateo County, CA
Crystal Springs Uplands School
Independent school · Grades 6–12
569 students
Hillsborough, CA
B+Overall grade569 students9 students per teacher
#9 Largest Private Schools in San Mateo County, CA
Woodside Priory School
Independent Catholic school · Grades 6–12
427 students
Portola Valley, CA
A+Overall grade427 students10 students per teacher
#10 Largest Private Schools in San Mateo County, CA
Highlands Christian Schools
Christian school (nondenominational) · Grades Pre-K–8
355 students
San Bruno, CA
BOverall grade355 students15 students per teacher
#11 Largest Private Schools in San Mateo County, CA
Synapse School
Independent school · Grades K–8
327 students
Menlo Park, CA
A+Overall grade327 students7 students per teacher
#12 Largest Private Schools in San Mateo County, CA
St. Catherine of Siena School
Parish school · Grades K–8
303 students
Burlingame, CA
A+Overall grade303 students17 students per teacher
#13 Largest Private Schools in San Mateo County, CA
St. Robert Catholic School
Parish school · Grades K–8
303 students
San Bruno, CA
B-Overall grade303 students23 students per teacher
#14 Largest Private Schools in San Mateo County, CA
St. Gregory School
Diocesan school · Grades K–8
297 students
San Mateo, CA
B+Overall grade297 students19 students per teacher
#15 Largest Private Schools in San Mateo County, CA
Our Lady of Angels School
Parish school · Grades K–8
296 students
Burlingame, CA
BOverall grade296 students17 students per teacher
#16 Largest Private Schools in San Mateo County, CA
Episcopal Day School of St. Matthew
Episcopal school · Grades Pre-K–8
290 students
San Mateo, CA
A+Overall grade290 students6 students per teacher
#17 Largest Private Schools in San Mateo County, CA
Sea Crest School
Independent school · Grades Pre-K–8
280 students
Half Moon Bay, CA
A-Overall grade280 students10 students per teacher
#18 Largest Private Schools in San Mateo County, CA
Woodland School
Independent school · Grades Pre-K–8
272 students
Portola Valley, CA
A+Overall grade272 students8 students per teacher
#19 Largest Private Schools in San Mateo County, CA
St. Charles School
Diocesan school · Grades K–8
263 students
San Carlos, CA
A+Overall grade263 students15 students per teacher
#20 Largest Private Schools in San Mateo County, CA
Stratford School
Independent school · Grades Pre-K–5
257 students
San Bruno, CA
B-Overall grade257 students18 students per teacher
#21 Largest Private Schools in San Mateo County, CA
The Primary School - East Palo Alto
Independent school · Grades Pre-K–6
255 students
East Palo Alto, CA
AOverall grade255 students5 students per teacher
#22 Largest Private Schools in San Mateo County, CA
The Carey School
Independent school · Grades Pre-K–5
252 students
San Mateo, CA
A+Overall grade252 students7 students per teacher
#23 Largest Private Schools in San Mateo County, CA
St. Dunstan Catholic School
Parish school · Grades K–8
246 students
Millbrae, CA
A+Overall grade246 students12 students per teacher
#24 Largest Private Schools in San Mateo County, CA
St. Raymond Elementary School
Diocesan school · Grades K–8
241 students
Menlo Park, CA
AOverall grade241 students11 students per teacher
From official public records, updated October 2026.