Summary:
Regional School District 17 is served by a single high school, Haddam-Killingworth High School, located in Higganum, CT, which educates approximately 466 students in grades 9–12. With only one high school in the district, all secondary students attend this small-to-midsize school, making it the sole focus of this analysis.
Haddam-Killingworth High School is a genuinely high-performing school, ranking 14th out of 133 Connecticut high schools for 2025–2026, placing it in the 89th percentile with a 5-star rating. The graduation rate is an impressive 97.6%, well above the state average of 91.2%, and the chronic absenteeism rate of 6.9% is less than half the state's 16.4%. On the SAT, 85.3% of 11th graders are proficient in English language arts versus the state's 55.3%, while math proficiency is 48.8% compared to the state's 31.1%. On the NGSS science test, 74.8% are proficient, well ahead of the state average of 50.5%. The school also benefits from a favorable student-teacher ratio of 9.5:1 and a low economic disadvantage rate, with only 13.7% of students eligible for free or reduced lunch.
While academics are strong across the board, math is the school's relative weak spot: during the 2024–2025 school year, ELA proficiency was 85.6% versus 48.8% for math, a 36.8-point gap that is wider than the state's 26.9-point gap. Still, Haddam-Killingworth High School exceeds state averages in every subject. The school has also steadily improved its ranking over three years, moving from 18th to 14th in Connecticut between 2023–2024 and 2025–2026 while maintaining 88th–89th percentile standing throughout. Per-student spending of roughly $19,388 (2018–2019) and the low student-teacher ratio indicate a well-resourced environment. Overall, this is a high-performing, stable school with excellent attendance, near-universal graduation, and strong results in English and science.
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