#1 Largest Private Schools in St. Clair County, IL
Althoff Catholic High School
Diocesan school · Grades 9–12
335 students
Belleville, IL
AOverall grade335 students15 students per teacher
2026 lists
Largest Private Schools in St. Clair County, IL
The private schools in St. Clair County, IL with the most students. Top 22 of 22 schools.
#2 Largest Private Schools in St. Clair County, IL
First Baptist Academy
Baptist school · Grades K–12
310 students
O'Fallon, IL
A-Overall grade310 students10 students per teacher
#3 Largest Private Schools in St. Clair County, IL
Zion Lutheran School
Lutheran (Missouri Synod) school · Grades Pre-K–8
256 students
Belleville, IL
BOverall grade256 students14 students per teacher
#4 Largest Private Schools in St. Clair County, IL
Holy Trinity Catholic School
Parish school · Grades Pre-K–8
204 students
Fairview Heights, IL
A+Overall grade204 students11 students per teacher
#5 Largest Private Schools in St. Clair County, IL
St. Teresa Catholic School
Diocesan school · Grades Pre-K–8
153 students
Belleville, IL
AOverall grade153 students11 students per teacher
#6 Largest Private Schools in St. Clair County, IL
Blessed Sacrament School
Parish school · Grades Pre-K–8
142 students
Belleville, IL
A+Overall grade142 students10 students per teacher
#7 Largest Private Schools in St. Clair County, IL
Our Lady Queen of Peace School
Parish school · Grades Pre-K–8
139 students
Belleville, IL
A+Overall grade139 students12 students per teacher
#8 Largest Private Schools in St. Clair County, IL
Holy Childhood of Jesus School
Parish school · Grades Pre-K–8
132 students
Mascoutah, IL
B+Overall grade132 students9 students per teacher
#9 Largest Private Schools in St. Clair County, IL
Illinois Center for Autism
Special education school · Ungraded
125 students
Fairview Heights, IL
BOverall grade125 students8 students per teacher
#10 Largest Private Schools in St. Clair County, IL
Illinois Center for Autism
Special education school · Ungraded
125 students
Fairview Heights, IL
BOverall grade125 students8 students per teacher
#11 Largest Private Schools in St. Clair County, IL
Unity Lutheran Christian Elementary School
Lutheran (Missouri Synod) school · Grades Pre-K–8
112 students
East Saint Louis, IL
B+Overall grade112 students10 students per teacher
#12 Largest Private Schools in St. Clair County, IL
Sister Thea Bowman
Diocesan school · Grades K–8
101 students
East Saint Louis, IL
AOverall grade101 students9 students per teacher
#13 Largest Private Schools in St. Clair County, IL
St. James Catholic School
Diocesan school · Grades Pre-K–8
81 students
Millstadt, IL
AOverall grade81 students9 students per teacher
#14 Largest Private Schools in St. Clair County, IL
Governor French Academy
Independent school · Grades Pre-K–12
73 students
Belleville, IL
AOverall grade73 students7 students per teacher
#15 Largest Private Schools in St. Clair County, IL
Notre Dame Academy of Belleville
Parish school · Grades Pre-K–8
67 students
Belleville, IL
BOverall grade67 students
#16 Largest Private Schools in St. Clair County, IL
St. John the Baptist School
Diocesan school · Grades Pre-K–8
64 students
Smithton, IL
A-Overall grade64 students9 students per teacher
#17 Largest Private Schools in St. Clair County, IL
JTC Academy West
Special education school · Grades 4–12
49 students
Centreville, IL
B+Overall grade49 students10 students per teacher
#18 Largest Private Schools in St. Clair County, IL
JTC Academy
Special education school · Grades 4–12
49 students
Centreville, IL
B+Overall grade49 students10 students per teacher
#19 Largest Private Schools in St. Clair County, IL
St. Joseph Catholic School
Diocesan school · Grades Pre-K–8
46 students
Freeburg, IL
A+Overall grade46 students5 students per teacher
#20 Largest Private Schools in St. Clair County, IL
Asp2 STEAM Academy
Alternative school · Grades Pre-K–3
40 students
Belleville, IL
B+Overall grade40 students10 students per teacher
#21 Largest Private Schools in St. Clair County, IL
Berean Christian School
Christian school (nondenominational) · Grades Pre-K–10
28 students
Fairview Heights, IL
A-Overall grade28 students9 students per teacher
#22 Largest Private Schools in St. Clair County, IL
Elite Scholars STEAM Academy
Independent school · Grades Pre-K–6
21 students
Swansea, IL
A-Overall grade21 students6 students per teacher
From official public records, updated October 2026.