Summary:
ZIP code 02150 (Chelsea, Massachusetts) has three high schools that all serve grades 9–12 and enroll 1,979 students combined. Chelsea High is by far the largest, with 1,649 students — about 83% of all high-school enrollment in this area — while Phoenix Academy Charter Public High School Chelsea enrolls 198 and Chelsea Opportunity Academy enrolls 132. Chelsea High and Chelsea Opportunity Academy belong to the Chelsea district; Phoenix Academy operates as its own charter district.
Outcomes vary dramatically among these schools. Chelsea High has the strongest current results: a 78.2% graduation rate, which is 8.1 points above the Chelsea district rate of 70.1%, and a 15.5% dropout rate that matches the district. Phoenix Academy has a 12.3% graduation rate and a 58.9% dropout rate — nearly four times Chelsea High's. Chelsea Opportunity Academy graduates 25.0% and drops out at 29.2%, both far worse than its own district averages. On 2025–2026 MCAS tests, Chelsea High reached 15.7% proficiency in ELA, 15.36% in math, 13.73% in science and 11.08% in biology — roughly a third of state levels. Phoenix was much lower, including 0% ELA and 5.56% math, and Chelsea Opportunity Academy has no test-score rows provided at all.
Spending and staffing do not line up neatly with results in this small group. Phoenix spends the most per student ($21,496) and has the highest student-teacher ratio (19.9); Chelsea High spends $17,676 with the lowest ratio (13.1); Opportunity spends $16,464 with a ratio of 18.7. Phoenix's rank history also swung dramatically, from 6th of 345 schools (98th percentile, 5 stars) in 2017–2018 to 341st of 353 (3rd percentile, 0 stars) in 2025–2026. Free/reduced lunch data is blank for all three schools, and with small cohorts yearly rates can be volatile.
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