[6] By 1925, after many failed attempts, an 18,000-square-foot (1,700 m2) building was finally constructed at 800 Porter Street, where the school is located to this day.

By the end of the decade, the school was equipped with wood, metal, industrial arts, and electrical shops.

The $24.5 million project added a three-story classroom addition and a fieldhouse, essentially doubling the building’s square footage to 300,000.

[6] Also in the late 1990s, filming took place at Lemont High School for the movie Save the Last Dance.

[6] With student enrollment continuing to grow each year, Lemont High School has undergone further expansion recently.

In 2005, the community passed a $29.6 million referendum allowing the school to start an expansion which included a new and improved auditorium, approximately 30 new classrooms, a new wood shop, a turf football field with improved lighting and expanded audience seating, an expanded cafeteria area, additional parking, safety upgrades, and much more.

Other areas of the school, mainly parking lots and roads, were completed in the summer months of 2008.

[5] Lemont High School's enrollment of nearly 1,400 students can choose from approximately 200 course offerings in nine departments.

Students are assigned to course levels based on test scores, past achievement, and teacher recommendation.

The addition has been added on their PLC days where students get a dedicated 30 minutes every Wednesday to talk about a variety of Lemont topics.

[11] The Academic Departments at Lemont High School are: The Director of Activities & Athletics is John Young.

Lemont competes in the South Suburban Conference (SSC) and is a member of the Illinois High School Association (IHSA), which governs most sports and competitive activities in the state.

The school sponsors interscholastic teams for young men and women in bowling, basketball, cross country, golf, soccer, tennis, track & field, and volleyball.

In the early 2000s, the Illinois Native American Bar Association notified the high school of its disapproval of the Injuns name.