Congressional School was founded by Evelyn and Malcolm Devers in the fall of 1939 as an independent, private primary school. In six months, the school’s enrollment of three, four, and five-year-olds, housed in a five-room house in the Westover Hills section of Arlington, had grown to forty. Within a year, the school moved to the Yeatman home at 3155 N. Pershing Drive in Arlington and was expanded to include Grades 1-4.

During the summer of 1942, the school moved to the estate that had been the home of General George Patton on Ft. Myer Hill at 1401 N. 12^th Street, Arlington. The facilities were expanded, and over the next fifteen years, enrollment increased to include students from Preschool through Grade 8. A second campus opened in Alexandria in the mid 1950’s at 500 W. Windsor Avenue to house students in preschool through Grade 4.

Ground was broken during the late 1950’s and construction of a junior-senior high school facility began on forty acres on Sleepy Hollow Road in the Falls Church section of Fairfax County. The Alexandria property was sold in the fall of 1959, and grades 4-12 moved to the new Sleepy Hollow Road campus. Preschool through 3rd grade remained at the Ft. Myer location in Arlington. A devastating fire destroyed the Arlington school in March 1960. All children except the preschool were moved to the Sleepy Hollow Road campus. Within a week of the fire, parents and friends of the school had refurbished outbuildings at the Devers’ forty-acre property at 600 S. Carlyn Springs Road in Arlington for use by the preschool. That summer, construction of an elementary building began on the Falls Church campus, and by the fall of 1960, all students in preschool through Grade 12 were at the Sleepy Hollow Road School. In June 1960, the first high school class graduated from Congressional School.

In 1979, Congressional School was reorganized by William W. Devers as Congressional School, a nonprofit corporation governed by a Board of Regents. In 1985, the Board resolved to focus its resources on the Lower & Middle School population and phased out the high school. In 1987, Congressional graduated its first 8^th Grade Class and its last 12^th grade class. Also in 1987 Congressional opened an Infant and Toddler Center.