Summary
Glenbrook North High School is a public high school serving grades 9–12 in Northbrook, in Chicago’s northern suburbs, with 2,111 students. SchoolDigger ranks it 10th of 620 Illinois schools for 2025–26, in the 98th percentile with five stars; among six nearby schools with data, it ranks second, behind New Trier Township H S Winnetka. The school’s current test results are well above state and district results, and mathematics is its clearest relative strength.
In grade 11 ACT results, Glenbrook North is well ahead of the state in ELA (87% versus 50%), math (86% versus 40%) and science (87% versus 48%), and it also exceeds Glenbrook HSD 225 by 4, 8 and 6 percentage points, respectively. Math has the largest advantage over the nearby-school average: 23 points, compared with 17 in ELA and 19 in science. It ranks second among nearby schools in ELA and math, just behind New Trier by 0.1 and 0.9 points, and first in science by 0.1 point. Grade 9 results lead nearby schools serving that grade; grade 10 results are also strong, though math is a relative dip, ranking third locally. Glenbrook North also has the lowest reported chronic absenteeism rate among nearby schools in 2025–26: 14%, versus the nearby average of 27%. Its 96% graduation rate is above the state’s 90%, but below several nearby schools.
Recent test-score changes are mixed: grade 9 PreACT ELA and math improved by 3 and 6 points from the prior year, while grade 11 ACT ELA and math fell by 3 and 1 points, and grade 10 PreACT math fell by 4. SchoolDigger’s statewide ranking for English Language Learner students rose sharply, from the 27th percentile in 2022–23 to the 94th percentile in 2024–25, indicating a much stronger result for this group on that measure. The reported student-teacher ratio is 13:1 in 2024–25, close to the nearby-school average of 13.0:1. As context, 4% of students were free/reduced lunch eligible in 2021–22, compared with a 24% average among nearby schools; this is an observation, not an explanation for academic results.
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