Summary:
Old Lyme, Connecticut is served by Regional School District 18, which operates three public schools — Mile Creek School (elementary), Lyme-Old Lyme Middle School, and Lyme-Old Lyme High School — serving roughly 972 students in grades K-12 in this affluent shoreline community. The district ranks 22nd out of 153 Connecticut districts with a 4-star rating, and all three schools exceed state proficiency averages in nearly every reported subject.
Mile Creek School is the district's standout, ranking in the 90th percentile statewide with remarkably low chronic absenteeism of just 3.7%, far below the district average of 10.1%. Its 5th graders posted 87.8% proficiency in ELA and 4th graders reached 83.3% in math. Lyme-Old Lyme Middle School shines in science, with 85.1% of 8th graders proficient in NGSS versus 50.9% statewide, but its ranking slipped from the 94th to 86th percentile. Lyme-Old Lyme High School was ranked 4th in Connecticut in 2024-2025 but dropped to 22nd in 2025-2026.
The high school's decline mirrors falling 11th grade ELA proficiency (91.9% to 80.0%) and science scores (80.2% to 72.9%), along with a 19.8% chronic absenteeism rate — nearly double the district average and above the state's 16.4%. Middle school math is volatile by grade, with 6th grade jumping from 43.5% to 63.5% while 7th grade fell from 82.8% to 62.4%. Notably, spending does not predict outcomes: Mile Creek spends the least per student ($20,923) yet posts the strongest results, while the middle school spends the most ($24,269) with the lowest student-teacher ratio. Science is the district's clearest strength, with proficiency well above state averages at all three grade levels. Overall, families in Old Lyme enjoy an excellent, well-resourced school system, with high school absenteeism and recent ranking declines as the main watchpoints.
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