The Thornton-Donovan School was founded in 1901 as The New Rochelle School and Kindergarten by Judge Martin Jerome Keogh. Judge Keogh's wife brought to his attention that a Kindergarten was desperately needed to serve their neighborhood of New Rochelle. Judge Keogh offered his office space at 247 Main Street, New Rochelle, New York as the school's first home.

A teacher was of course needed, and Emily Scott Thornton, a graduate of the University of Nottingham, UK answered the Keogh's call. Off to a wonderful start and growing in popularity, Cleophe Donovan joined the school in 1904 to teach the incoming youngsters, while Ms. Thornton moved up with the older children.

In recognition of their commitment to their vision and years of dedicated service, the school was renamed in their honor, Thornton-Donovan School.

Ms. Thornton retired in 1945, and the reins were handed over to Genevieve F. Burns (for whom the school's library is named). Over the years, the school had grown significantly, and a larger space was necessary. In 1967 the school's current site, the red brick mansion at 100 Overlook Circle was selected. Thornton-Donovan had found its new home in the New Rochelle community which had been so important to its history.

In 1968, Douglas E. Fleming, Jr., a graduate of Iona College and Columbia University, was chosen to take the helm. Ms. Thornton's philosophies and the essential spirit of the school have been faithfully carried out by Mr. Fleming for more than 40 years. During this time, Mr. Fleming has been responsible for the education and guidance of thousands of students, from down the road and across the globe. He continues to serve the school in Ms. Thornton's same "...free and generous...kindly, humorous spirit" that she said "has been the very life of all our work."