STEM School Highlands Ranch, formerly known as STEM School and Academy, is a public charter school with a curriculum focused on Science, Technology, Engineering, and Mathematics (STEM), located in Highlands Ranch, Colorado. The school building is located in an office park next to Central Park,^[2] a retail center. The school serves as a K–12 for over 1,700 students from across the Denver Metro Area.

The school originally opened as STEM School and Academy to 480 students, grades 6–9, o August 15, 2011.^[3] It was led by principal David Floodeen.^[3][4] In 2012, the board of directors hired Dr. Penny Eucker as executive director. A grade was added every year until they had grades 6-12 in 2014. That year, STEM finished its renovations and turned its gym into a two-story high school, containing a weight room, art room with kiln, and a chemistry lab. In the years since opening, the school moved from being ranked one of the lowest-performing in Colorado to number 10th in the state (SAT Scores). And ranked 9th in the country by US News, and World Report.^[4]

STEM's first graduating class consisted of 1 student in 2015. The board of directors wanted to expand, which resulted in the leasing and remodeling of the conjoining building and adding the first 5th grade class in fall of 2015.^[4] Of the original 113 5th graders, only 25 remained at STEM for the rest of their elementary, middle, and high school educations and graduated as the class of 2023, these students were known as the "Original 5th graders"

Grades K-4 were added in fall of 2016, officially making the school a K-12.^[4] Becoming a part of KOSON Schools in 2017, the school re branded and changed its name to STEM School Highlands Ranch, adopted a new tagline, new mission statement, and new logo.^[4]

In 2018, anti-suicide programs were implemented to help lower chances of suicide and school shootings.

In the fall of 2019, STEM School Highlands Ranch purchased the building that housed grades K–5.

In the fall of 2020, STEM purchased the neighboring building to house its P-TECH program (Grades 13 and 14) and the Business Offices for STEM School Highlands Ranch as well as the Charter Network Main Offices of KOSON Network of Schools.

The main school buildings have three engineering labs, four computer labs, a chemistry lab, a weight room, two gyms (Secondary and Elementary), and three parking lots which encase the building on all but the north sides of the school facility. The eastern side of the school has a playground for grades K-5. The north side of the building has a recreation area with picnic tables where high school students can eat lunch. South of the elementary building there is a small building for the P-TECH college course, there are 3 classrooms primarily for P-TECH courses, however some high school level classes are held in this building.

KOSON Network of Schools was founded in 2017, and is a collection of charter schools in Colorado. Currently, there is only one school in their network, STEM School Highlands Ranch. Two other proposed schools, STEM School Denver and STEM School Sterling Ranch, have been denied by Denver Public Schools and Douglas County School District.

The efforts for replicating the flagship campus of STEM Highlands Ranch began in earnest in the fall of 2021, the school hired a Replication Officer and officially organized KOSON as the Charter Network organization. The applications for STEM School Denver (K-5) and STEM School Sterling Ranch (K-12) were submitted in March of 2022, however, the applications were denied by Denver Public Schools and Douglas County School District RE-1.

KOSON currently operates inside STEM School Highlands Ranch's P-TECH building, also known as the Charter Network Main Offices.^[7]

Gitanjali Rao (Class of 2023), 2020 Time Kid Of The Year, Inventor^[10]

A shooting incident on May 7, 2019, left one student dead and eight others injured.^[11] The shooting was carried out by two students from the school.^[12]