#1 Largest Private Schools in Lower Connecticut River Valley County, CT
Mercy High School
Diocesan school · Grades 9–12
384 students
Middletown, CT
AOverall gradeAll girls384 students12 students per teacher
2026 lists
Largest Private Schools in Lower Connecticut River Valley County, CT
The private schools in Lower Connecticut River Valley County, CT with the most students. Top 8 of 8 schools.
#2 Largest Private Schools in Lower Connecticut River Valley County, CT
St. John Paul II School
Diocesan school · Grades Pre-K–8
199 students
Middletown, CT
AOverall grade199 students12 students per teacher
#3 Largest Private Schools in Lower Connecticut River Valley County, CT
Yeshiva Gedolah of Waterbury- Mesivta Durham
Religious school · Grades 9–12
147 students
Durham, CT
B-Overall gradeAll boys147 students23 students per teacher
#4 Largest Private Schools in Lower Connecticut River Valley County, CT
The Independent Day School
Independent school · Grades Pre-K–8
89 students
Middlefield, CT
AOverall grade89 students5 students per teacher
#5 Largest Private Schools in Lower Connecticut River Valley County, CT
Franklin Academy
Special education school · Grades 8–12
77 students
East Haddam, CT
BOverall grade77 students4 students per teacher
#6 Largest Private Schools in Lower Connecticut River Valley County, CT
St. John School
Parish school · Grades Pre-K–7
55 students
Old Saybrook, CT
A+Overall grade55 students3 students per teacher
#7 Largest Private Schools in Lower Connecticut River Valley County, CT
The Children's Tree Montessori School
Montessori school · Grades Pre-K–6
40 students
Old Saybrook, CT
B+Overall grade40 students7 students per teacher
#8 Largest Private Schools in Lower Connecticut River Valley County, CT
The Oxford Academy
Alternative school · Grades 9–12
35 students
Westbrook, CT
AOverall gradeAll boys35 students1 students per teacher
From official public records, updated October 2026.