Marjory Stoneman Douglas High School (MSDHS) is a public high school in Parkland, Florida, United States. Established in 1990 as part of the Broward County Public Schools district and named after the writer Marjory Stoneman Douglas, it was the only public high school in Parkland, serving almost the entire city as well as a small section of neighboring Coral Springs.

On February 14, 2018, the school was the scene of a deadly mass shooting perpetrated by a 19-year-old former student of the school, in which fourteen students and three staff members were murdered, and seventeen others were injured. On June 14, 2024, the building where the shooting took place was demolished.

Marjory Stoneman Douglas High School was named after the Everglades environmentalist Marjory Stoneman Douglas. The school is located just under two miles (3.2 km) from the Everglades National Park, on part of the historical Everglades for which Marjory Stoneman Douglas advocated. The school opened in 1990, the year of her centennial, with students in grades 9 through 11, most of whom transferred from nearby schools Coral Springs High School and J. P. Taravella High School. The first senior class graduated in 1992.

On February 14, 2018, a mass shooting at the campus perpetrated by a 19-year-old former student of the school armed with a semi-automatic AR-15 style rifle left 17 dead and 17 more wounded in less than six minutes. Cruz was apprehended an hour later. At the time, it was the deadliest high school shooting in U.S. history, surpassing the Columbine High School massacre on April 20, 1999, in which 13 people were killed. In 2016, a MSDHS school resource officer and Broward County Sheriff's Office deputy had an investigator for the Florida Department of Children and Families (FDCF) speak to Cruz, but Cruz's therapist said that he was "not currently a threat to himself or others" and did not need to be committed. A mental health counselor said that Cruz did not meet the criteria under Florida law that allows the police to commit a mentally ill person against their will. MSDHS conducted a "threat assessment" on Cruz after the counselor's report, and the FDCF ultimately concluded that Cruz was not a threat because he was living with his mother, attending school, and seeing a counselor.

Authorities charged Cruz with first-degree murder, and the case went to trial in September 2021 along with the case of an attack by Cruz against a jail officer. On October 20, 2021, Cruz pleaded guilty to all charges, including murder and attempted murder. On November 2, 2022, Cruz was sentenced to 34 consecutive life sentences without the possibility of parole, one life sentence for each of the victims whom Cruz murdered and wounded.

Students from MSDHS were instrumental in helping organize nationwide student protests following the shooting, and in spurring the revision of Florida law on March 4, 2018, to raise the legal rifle-owner age from 18 to 21, with a three-day wait.

The building where the shooting occurred was permanently closed, and it served as evidence at the subsequent murder trial. Demolition of the structure began on June 14, 2024. The project was completed on July 5. Future plans for the site have not been finalized.

The Marjory Stoneman Douglas Athletics Department operates programs in football, volleyball, lacrosse, softball, tennis, track, water polo, bowling, basketball, cheerleading, soccer, wrestling, swimming, cross country, and golf.