Schools in Zip Code 06807

Zip code 06807, covering Cos Cob, Connecticut, contains exactly one school: Cos Cob School, a public elementary school serving grades PK–5 with 343 students in the Greenwich School District. As the only school in the zip code, it is the area's standout by default, but it earns that label on its own merits. Cos Cob School rose from a 3-star to a 4-star rating for 2025–2026 and jumped from a state rank of 159 out of 497 (68th percentile) to 102 out of 491 (79th percentile) in a single year — a gain of 57 places that moves it into the top quarter of Connecticut elementary schools.

Academically, Cos Cob School far exceeds state averages while trailing its own district. In 2025–2026, average ELA proficiency across grades 3–5 is 73.1% versus 50.6% statewide, and average math proficiency is 68.7% versus 50.0% statewide. Both figures sit below the Greenwich School District averages of 82.7% and 82.3%, respectively. Third grade is a clear strength, with 77.2% proficiency in both ELA and math — the school's best results, including a striking +18.9-point ELA improvement over last year. Upper-elementary math is a relative weak spot: 4th-grade math proficiency is 62.9% and 5th-grade math is 65.9%, both well below district levels. Science comes closest to district parity at 77.3%, just 1.6 points behind.

The school's fundamentals are strong. The student-teacher ratio is a favorable 10:1, and chronic absenteeism is just 6.0% — less than half the state rate of 16.4% and below the district's 8.5%. The free/reduced lunch rate of 16% reflects a relatively low-poverty student population, and per-student spending exceeds $22,000. One concern is a possible cohort effect in math: current 4th graders dropped from 73.3% proficiency in 3rd-grade math to 62.9%, while current 5th graders fell from 72.3% to 65.9%. Families should also note that 06807 has no middle or high schools, so secondary students attend schools outside the zip code. Overall, Cos Cob School is high-performing and upward-trending, with upper-elementary math as its main opportunity for growth.