Breaking up Los Angeles City School District is nothing new to Santa Clarita Valley residents. In 1944, local families, tired of having students bused to San Fernando High School, gained the right to establish their very own secondary schools.

The following year, a group of 73 ninth graders set up a school using part of the existing Newhall Elementary campus to become the first high school class in the new William S. Hart Union High School District. Ironically, the area was originally given the title the Santa Clarita High School District, but the name was soon changed to honor William S. Hart, the local western film star and community benefactor.

Reportedly, Hart was very touched by the board of education naming both district and school after him, for he had suggested General Fremont High School. And although it is said that cowboy actor Hart's affinity for Indians was well known, it had no bearing on the new school's nickname. According to committee member Gwen (Booth) Gallion, it was in the spring of 1946 that students selected the nickname Indians and maroon and gray for school colors. Gwen says the process was one of choosing symbols that would distinguish Hart from a chalkboard list of banners that represented existing nearby schools. Colors were changed to red and black in the sixties because of difficulty in matching maroon hues.

Buildings on the current site were opened in spring 1946, with the landmark gymnasium being completed three years later, the same year as Hart's first senior class, the 49ers, graduated. Growth and facility upgrading and improvements have changed the face of the campus in recent years, but the 1994 earthquake, which prompted the demolition of the gym and condemned the administrative offices, has had the greatest effect on campus appearance.

Prime movers in shaping the fledging school's development included local school board members and Superintendent/Principal Lester Dalbey. Among the early faculty names were those of Homer Anderson, Margaret Haskell, Russell Johnson, Norma Lewis, Helen Nosker, Helen Pfister, Lois Phillips, Hazel Snow, and a gentleman soon to be known as Father Hart, Cecil Sims. Sims would sponsor much of the school's ASB and activity program and write the Alma Mater.

Following Dalbey, and providing caring administrative leadership for a record tenure of 16 years (1949-1965) was Principal George W. Harris. Currently, the position is held by Dr. Collyn Nielsen who took the helm in 2007.