Truman High School is one of the remaining large high schools in the Bronx that has not been phased out and broken up into a number of small schools. This trend, which has been popular in the city, has seen other high schools in the borough, such as Evander Childs High School and Roosevelt High School closed and split into a number of smaller schools located in the same building. The school does, however, host Bronx Health Sciences High School created as part of the small schools movement, and previously hosted two additional high schools which have since moved to other locations. Truman High School and Bronx Health Sciences compose Harry S. Truman Educational Campus.
The site of Truman High School and the rest of Co-op City was originally home to the Freedomland amusement park. In the mid-1960s, when Co-op City was being constructed, the city proposed to construct a large high school in the development as well as Herbert H. Lehman High School and Adlai E. Stevenson High School in eastern Bronx, John F. Kennedy High School in western Bronx, South Shore High School in Brooklyn, and August Martin High School in Queens. Both Truman and Kennedy High Schools were planned as "educational parks", containing multiple schools in park settings, and integrating students from multiple areas and backgrounds to stave off de facto segregation within the school system. Truman's academic park was also called "Northeast Bronx Educational Park" or "East Bronx Educational Park", with a total of five schools planned in the complex to serve 10,400 students from both Co-op City and surrounding neighborhoods. The Northeast Bronx Park was funded by a grant as part of the Elementary and Secondary Education Act, and was to be the prototype for numerous academic parks in other parts of the city. The project was sponsored and developed by the United Housing Foundation and RiverBay Corporation, who also developed Co-op City.
Construction on the complex began in 1969. During this time, a shopping center within the neighborhood was used as a temporary elementary school for local students. The first school completed within the park, PS 153, opened on September 13, 1971. The three remaining elementary and intermediate schools opened by September 1972. Truman High School opened on September 10, 1973, along with Beach Channel High School in Rockaway, Queens. The entire project cost $76 million. The completion of the athletic field was delayed due the 1970s fiscal crisis. Soon after opening, the buildings of the complex were found to have numerous structural problems including leaks, cracking, and faulty utilities. The complex was boycotted by local residents in 1975 until repairs were made. The issues led New York State Comptroller Edward V. Regan to audit the complex in late 1979.
In 1998, Sana Q. Nasser became the principal of Truman. Under a partnership with the non-profit organization "P.E.N.C.I.L.", she has created six small career-themed academies in TV Production/Media Communications, Culinary Arts, Air Force Junior ROTC, Engineering & Robotics, Law, and Business Computing. The academies serve to create and maintain the benefits and feeling of a small high school, with the variety of courses and extracurricular activities that can only be offered at a large high school. Students take their academy classes every day, for all four years of high school and change academies (or enroll in more that one), if their schedule permits. Statistical analysis done by the school has indicated that among students who participate in the academies, on-time graduation rates are significantly higher, and overall attendance, behavior and academic performance in the core subject areas has improved.
As part of the small schools movement championed by Mayor Michael Bloomberg and the Department of Education, three additional small high schools were opened within the Truman facility in September 2004: Bronx Health Sciences High School, East Bronx Academy for the Future, and Performance Conservatory High School (aka Bronx High School for Performance and Stagecraft). Truman was retained as a large high school. East Bronx Academy was moved to a new building in Crotona Park East in 2005, while Performance Conservatory is now part of the Herman Ridder Educational Campus and in the process of closing.
On June 18, 2009, during his bid for re-election, Mayor Bloomberg claimed that during his administration, reported crimes at the school had dropped by a staggering 85%.
On September 6, 2013, Principal Sana Q. Nasser retired from her post as leader of the school.