With the increase in population of Valhalla due to the construction of nearby Kensico Dam (whose reservoir provides water to New York City), the small schools which had served the community until then became too small. In 1918, North White Plains built a school along Route 22 (this building closed as a school in 1976 and is now an office building), and in 1919, Columbus Avenue School was built.

At the time, Columbus Avenue School housed students up through 8th grade (13-14 yrs. old), and was only the central portion of the present building. In 1923, the Columbus Avenue School and the North White Plains Elementary School consolidated to form the Valhalla School District.

A large addition to CAS, undertaken in 1928, added a wing to each end of the original building. One housed 4 classrooms and a stairwell; the other 2 classrooms, a stairwell, an auditorium, and a gymnasium. A renovation project in 1990-91 altered some of the interior layout of the building, but the building itself has remained as it was after the 1928 addition. Elsewhere in the District, a junior high school was built in 1952, another elementary school (Virginia Road) was built in 1958, and the junior high was expanded to become the high school as well in 1961.

Once the junior high was built, CAS housed students from Kindergarten (ages 5-6) through 6th (ages 11-12) and later 5th grades (ages 10-11). With the 1995-96 school year, Virginia Road Elementary School became the building for all of the District's Kindergarten through 2nd grade (7-8 yrs. old), and Columbus Ave. now has only 3rd (ages 8-9) through 5th grade students. Also during the 1995-96 school year, CAS celebrated its 75th anniversary as a school with activities and special events throughout the year.

The 2001-2002 school year, its 83rd with students, marked the close of a long chapter in Valhalla schools history. In November of that year, Valhalla's 3rd to 5th grade students moved to their new home at Kensico School. The top floor of Columbus Avenue School is to be rented out and will become BOCES offices; the lower floor is to house a day care facility. The ownership of the entire building is retained by the District so that residents can continue to make use of its facilities.