In 1950 Diana Hanbury King (pictured right) came to this country. She began teaching at Sidwell Friends School in Washington D.C. At the time this was one of several schools that had a program for dyslexic students under the aegis of Anna Gillingham. The program was directed by Helene Durbrow, who had been trained by Dr. Samuel Orton.

With encouragement from Dr. Orton, Helene Durbrow had opened Camp Mansfield, a summer program for dyslexic students in Vermont. Mrs. King spent several summers there and in due course was inspired to found Dunnabeck, in Western Pennsylvania. After running the camp for fourteen years, she met Kurt Goldman (pictured below), who encouraged her to open a school for dyslexic students and offered to provide the necessary funding.

In 1969 Kildonan opened in Bucks County on a rented campus in Solebury. The first year, twelve students enrolled, but the school flourished and eventually outgrew the facility. Under the leadership of Leisket Mills, then chair of the Board of Trustees, a search began for a new campus. In 1980 the school moved to its present quarters in Amenia, New York, in the foothills of the Berkshires. The 460 acre campus had been the site of Barlow School and had several dormitories, a schoolhouse, a library, and an art building. In 1983 the summer program moved from Pennsylvania and became a part of the school. Over time, with the support of the trustees, Kildonan was able to add a large boys’ dormitory, a girls’ dormitory, and an elementary building housing day students in grades one through six. The school's most recent addition was an impressive athletic center that now welcomes families at the main entrance of campus.