History
While Bernard Fulton was assistant headmaster at the St. Mark's School of Texas, he had an idea to create a co-educational school in Dallas. Thus, Greenhill School was founded in 1950 as a co-educational option in the bubble of independent schools in Dallas. From 1950-1976, Bernard served as the founding headmaster, and at the time, he introduced the concepts of independent co-education, the primer program, and open-space education while the school grew from 62 students to 1,002. After he retired from Greenhill School, he became the headmaster of Lakehill Preparatory School and later, Fulton Academy in Rockwall, Texas was named after him as well. On October 20, 1990, Governor Bill Clements implemented Bernard Fulton Day “for his dedication to the education of young people in Dallas, in Texas, and in the nation."

In 2011 Greenhill took 50% more students from within the Plano Independent School District boundaries than it did in 2010. Increased concerns with demographic changes, state budget cuts, and larger school populations in the Plano ISD schools resulted in increased interest in private schools like Greenhill from parents living within Plano ISD.