Glenbrook South High School underwent a significant expansion in 2002, adding dozens of classrooms, revamping the music and performing art facilities, and reconfiguring the parking lots and athletics fields.

A new Food Court was constructed along with a Student Activities Center that was created by reconfiguring the faculty lounge.

Several new classrooms, including all the science labs, gymnasium basketball hoops, wrestling mats, and the athletic bathrooms have been remodeled in the 2022-2023 year.

[8] According to 2019 statistics, Glenbrook South was ranked 17th in terms of the best public high schools in the state of Illinois.

[10] The Federal No Child Left Behind Act as applied in Illinois requires 100% of students to meet standards on the Prairie State Achievement Exam by 2013.

Glenbrook South High School continues to focus curricular efforts on academic growth for each student.

GBS sponsors interscholastic teams for young men and women in basketball, cross country, golf, gymnastics, soccer, swimming, fencing, diving, tennis, track & field, volleyball, and water polo.

[12] The following teams have won state championships:[13] GBS sponsors a number of activities for students ranging from cultural and artistic to academic and social welfare.

[15] The following activities won their respective IHSA sponsored state tournament or competition:[13] Glenbrook South was also named the 2008 National GRAMMY Signature School for its music program.

Founded in 1981 to give students a more unorthodox learning perspective, it covers English, Social Studies, and a foreign language.