Serving 343 students in grades Prekindergarten-5, Cos Cob School ranks in the top 30% of all schools in Connecticut for overall test scores (math proficiency is top 20%, and reading proficiency is top 20%).
The percentage of students achieving proficiency in math is 65-69% (which is higher than the Connecticut state average of 41%). The percentage of students achieving proficiency in reading/language arts is 65-69% (which is higher than the Connecticut state average of 50%).
The student-teacher ratio of 10:1 is lower than the Connecticut state level of 12:1.
Minority enrollment is 33% of the student body (majority Hispanic), which is lower than the Connecticut state average of 54% (majority Hispanic).
Quick Facts (2026)
- Grades: Prekindergarten-5
- Enrollment: 343 students
- Student-Teacher Ratio: 10:1
- Minority Enrollment: 33%
- Overall Testing Rank: Top 30% in CT
- Math Proficiency: 65-69% (Top 20%)
- Reading Proficiency: 65-69% (Top 30%)
- Science Proficiency: 55-59% (Top 50%)
- Source: National Center for Education Statistics (NCES), CT Dept. of Education
Top Rankings
Cos Cob School ranks among the top 20% of public schools in Connecticut for:
Category
Attribute
Most improved public schools
Math Proficiency
Student Attention
School Overview
Cos Cob School's student population of 343 students has declined by 5% over five school years.
The teacher population of 34 teachers has grown by 9% over five school years.
Grades Offered
Grades Prekindergarten-5
(Supplemental Virtual)
(Supplemental Virtual)
Total Students
343 students
Total Classroom Teachers
34 teachers
Year Founded
1915
Campus Size
6 acres
School Motto
Our Mission Cos Cob School is a collaborative community of learners dedicated to academic excellence, personal integrity, and interpersonal responsibility.
School Rankings
Cos Cob School ranks within the top 30% of all 939 schools in Connecticut (based off of combined math and reading proficiency testing data).
The diversity score of Cos Cob School is 0.51, which is less than the diversity score at state average of 0.68. The school's diversity has stayed relatively flat over five school years.
Overall Testing Rank
#193 out of 939 schools
(Top 30%)
(Top 30%)
Math Test Scores (% Proficient)
65-69%
41%
Reading/Language Arts Test Scores (% Proficient)
65-69%
50%
Science Test Scores (% Proficient)
55-59%
47%
Student-Teacher Ratio
10:1
12:1
American Indian
1%
n/a
Asian
5%
5%
Hispanic
21%
32%
Black
1%
12%
White
67%
46%
Hawaiian
n/a
n/a
Two or more races
5%
5%
All Ethnic Groups
Eligible for Free Lunch
13%
38%
Eligible for Reduced Lunch
3%
6%
School Statewide Testing
School District Name
Source: National Center for Education Statistics (NCES), CT Dept. of Education
School Notes
- School Mascot: Phoenix
Frequently Asked Questions
What is Cos Cob School's ranking?
Cos Cob School is ranked #193 out of 939 schools, which ranks it among the top 30% of public schools in Connecticut.
What percent of students have achieved state testing proficiency in math and reading?
65-69% of students have achieved math proficiency (compared to the 41% CT state average), while 65-69% of students have achieved reading proficiency (compared to the 50% CT state average).
How many students attend Cos Cob School?
343 students attend Cos Cob School.
What is the racial composition of the student body?
67% of Cos Cob School students are White, 21% of students are Hispanic, 5% of students are Asian, 5% of students are Two or more races, 1% of students are American Indian, and 1% of students are Black.
What is the student-teacher ratio of Cos Cob School?
Cos Cob School has a student ration of 10:1, which is lower than the Connecticut state average of 12:1.
What grades does Cos Cob School offer ?
Cos Cob School offers enrollment in grades Prekindergarten-5 (Supplemental Virtual).
What school district is Cos Cob School part of?
Cos Cob School is part of Greenwich School District.
School Reviews
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