Building 21

Building 21 is a tight-knit high school in Philadelphia, Pennsylvania, part of Philadelphia City SD. The school instructs 371 students in grades 9 through 12. That puts it 50% leaner than the typical public school in Pennsylvania, which averages around 738 students.

Within Philadelphia City SD, which oversees 220 schools and 116,230 students, Building 21 is one campus in the system.

On demographics, Building 21 logs that the student body is overwhelmingly Black (91%). Beyond that, the school reports 5% Hispanic, 2% multiracial. The wider county runs roughly 39% Black, putting the school's mix meaningfully more Black than the area baseline.

On the income-and-resources front, Building 21 reports 18 full-time-equivalent teachers, putting the student-to-teacher ratio at about 20.5:1. Statewide, the average ratio sits near 12.8:1, putting Building 21 higher than the state norm the norm. Roughly 103% of students at Building 21 qualify for free or reduced-price lunch, which schools and policymakers use as a rough income-mix signal. Set against Philadelphia County (around 95%), the school's rate is noticeably above typical.

After controlling for student poverty, On a poverty-adjusted basis, Building 21 sits in the bottom 10% statewide. Predicted proficiency from the FRL regression is roughly 33.5%; actual is 10.1%, a gap of -23.4 points.

Across the wider county, Philadelphia County reports that the typical household earns roughly $61,953 per year, 35% of adults hold a bachelor's degree or higher, and roughly 17% of residents live below the federal poverty line. In all, Philadelphia County runs 309 public schools (combined enrollment of about 182,005 students), of which Building 21 is one.

The closest other public school is Wagner Gen Louis MS, roughly 0.3 miles away. Within five miles, there are 8 other public schools. On composite proficiency, Building 21 comes 7th of 9 in the immediate cluster, beneath the nearby-schools average of 16.8%.

Building 21 operates from an urban location.

Five-year trend. Looking back 7 years, enrollment at Building 21 has ticked up 4%, going from 357 students in 2018 to 371 in 2025. The Black share of enrollment climbed from 75% to 91% over that span. Class-load math has fell: from 27.8:1 in 2018 to 20.5:1 in 2025.

On this page, posts here usually surface around pickup logistics, teacher feedback, and after-school programs. The community welcomes input from current and former families.