#1 Largest Private Schools in Union County, NJ
Kent Place School
Independent school · Grades Pre-K–12
636 students
Summit, NJ
A+Overall gradeAll girls636 students7 students per teacher
2026 lists
Largest Private Schools in Union County, NJ
The private schools in Union County, NJ with the most students. Top 34 of 34 schools.
#2 Largest Private Schools in Union County, NJ
Union Catholic Regional High School
Diocesan school · Grades 9–12
530 students
Scotch Plains, NJ
A+Overall grade530 students10 students per teacher
#3 Largest Private Schools in Union County, NJ
Oak Knoll School of the Holy Child
Independent Catholic school · Grades Pre-K–12
498 students
Summit, NJ
A+Overall grade498 students6 students per teacher
#4 Largest Private Schools in Union County, NJ
Oratory Prep School
Independent Catholic school · Grades 7–12
363 students
Summit, NJ
A+Overall gradeAll boys363 students9 students per teacher
#5 Largest Private Schools in Union County, NJ
St. Michael Parish School
Parish school · Grades Pre-K–8
329 students
Union, NJ
B+Overall grade329 students15 students per teacher
#6 Largest Private Schools in Union County, NJ
Holy Trinity
Diocesan school · Grades Pre-K–8
303 students
Westfield, NJ
AOverall grade303 students12 students per teacher
#7 Largest Private Schools in Union County, NJ
St. Michael School
Diocesan school · Grades Pre-K–8
258 students
Cranford, NJ
BOverall grade258 students16 students per teacher
#8 Largest Private Schools in Union County, NJ
Jewish Educational Center Lower School
Jewish day school · Grades Pre-K–5
221 students
Elizabeth, NJ
BOverall grade221 students8 students per teacher
#9 Largest Private Schools in Union County, NJ
Bruriah High School for Girls
Jewish day school · Grades 6–12
213 students
Elizabeth, NJ
A+Overall gradeAll girls213 students4 students per teacher
#10 Largest Private Schools in Union County, NJ
Rav Teitz Mesivta Academy (Jec High School)
Jewish day school · Grades 6–12
210 students
Elizabeth, NJ
B-Overall gradeAll boys210 students14 students per teacher
#11 Largest Private Schools in Union County, NJ
Mother Seton Regional High School
Diocesan school · Grades 9–12
181 students
Clark, NJ
A+Overall gradeAll girls181 students8 students per teacher
#12 Largest Private Schools in Union County, NJ
St. Joseph the Carpenter School
Diocesan school · Grades Pre-K–8
160 students
Roselle, NJ
AOverall grade160 students12 students per teacher
#13 Largest Private Schools in Union County, NJ
St. Bartholomew Academy
Parish school · Grades Pre-K–8
157 students
Scotch Plains, NJ
A+Overall grade157 students11 students per teacher
#14 Largest Private Schools in Union County, NJ
Academy of Our Lady of Peace
Parish school · Grades Pre-K–8
125 students
New Providence, NJ
A+Overall grade125 students9 students per teacher
#15 Largest Private Schools in Union County, NJ
Cornerstone Day School
Special education school · Grades 6–12
125 students
Cranford, NJ
B+Overall grade125 students7 students per teacher
#16 Largest Private Schools in Union County, NJ
Flexschool
Independent school · Grades K–12
98 students
Berkeley Heights, NJ
A+Overall grade98 students3 students per teacher
#17 Largest Private Schools in Union County, NJ
Newmark High School
Special education school · Grades 1–8
96 students
Scotch Plains, NJ
B+Overall grade96 students7 students per teacher
#18 Largest Private Schools in Union County, NJ
Newmark School
Special education school · Grades 1–8
90 students
Scotch Plains, NJ
BOverall grade90 students8 students per teacher
#19 Largest Private Schools in Union County, NJ
Honor Ridge Academy
Special education school · Grades 1–12
89 students
Clark, NJ
BOverall grade89 students7 students per teacher
#20 Largest Private Schools in Union County, NJ
Harmony Christian Academy
Christian school (nondenominational) · Grades Pre-K–11
83 students
Elizabethport, NJ
BOverall grade83 students10 students per teacher
#21 Largest Private Schools in Union County, NJ
First Children School
Special education school · Grades Pre-K–12
78 students
Plainfield, NJ
A+Overall grade78 students5 students per teacher
#22 Largest Private Schools in Union County, NJ
Jardine Academy
Special education school · Grades Pre-K–12
71 students
Cranford, NJ
B+Overall grade71 students6 students per teacher
#23 Largest Private Schools in Union County, NJ
Salahuddin Future Academy, Plainfield Branch
Islamic school · Grades Pre-K–12
70 students
Plainfield, NJ
B+Overall grade70 students5 students per teacher
#24 Largest Private Schools in Union County, NJ
St. Pauls Day School
Early childhood program · Grades Pre-K–K
70 students
Westfield, NJ
B+Overall grade70 students18 students per teacher
From official public records, updated October 2026.