O Fallon High School

O Fallon High School is a sizable senior high in O Fallon, Illinois, overseen by O Fallon Twp HSD 203. The school educates 2,540 students in grades 9 through 12. Enrollment runs roughly 205% above the state mean of about 834.

Operationally, O Fallon High School answers to O Fallon Twp HSD 203, which sets policy, hires staff, and reports enrollment to the state.

On demographics, O Fallon High School reports that 59% of the student body identifies as White; the rest consists of 20% Black, 9% multiracial, 8% Hispanic, 2% Asian. That composition is broadly in line with St. Clair County as a whole.

On the resource side, The school reports having 156 full-time-equivalent teachers, for a student-teacher ratio near 16.3:1. The state averages around 13.8:1, so this campus is higher than the state norm typical. Roughly 28% of students at O Fallon High School qualify for free or reduced-price lunch, a number frequently used as a low-income enrollment indicator. Set against St. Clair County (around 54%), the school's rate is noticeably below typical.

On a residual basis (actual vs predicted given the student mix), O Fallon High School tracks the demographic baseline. The model predicts 55.3% given the school's FRL share; actual proficiency is 51.7%.

Zooming out to the county, community-level numbers for St. Clair County indicate median household income runs about $73,854, roughly 32% of adults have completed at least a four-year degree, and roughly 10% of residents live below the federal poverty line. In all, St. Clair County runs 96 public schools (combined enrollment of about 40,879 students), of which O Fallon High School is one.

Nearest neighbor: Laverna Evans Elem School, around 0.6 miles off. Counting just inside five miles, 8 other public schools cluster around O Fallon High School. On composite proficiency, O Fallon High School comes 7th of 9 in the immediate cluster, below the nearby-schools average of 59.3%.

The school occupies an outer-ring site.

Over the past 7-year window. Over the past 7-year window, the student count rose 5%: 2,409 students in 2018 compared to 2,540 in 2025. Over the same period, the White share shrank from 66% to 59%. Class-load math has tightened: from 18.3:1 in 2018 to 16.3:1 in 2025.

On this page, members of the O Fallon High School community share and discuss open house dates, ride-share offers, and field-trip permission slips. Contributors range from current parents to recent graduates and teachers.