Frances Ilg

Frances Lillian Ilg, MD, was born in Oak Park, Illinois. A pediatrician and professor at Yale, Ilg was a pioneering scholar in infant and child development and cofounder and first director (1950) of the Gesell Institute of Child Development (now the Gesell Institute of Human Development) and recipient of the Snow award for Distinguished Service to Humanity.

Ilg came from a large family. It was remarked by Gesell that she may have learned to value collaboration and  question  the  predominant  behavioral  paradigm due to her large natal families. She graduated from Wellesley in 1925 and Cornell Medical School as a pediatrician in 1929. She interned at Saint Mary’s Hospital for Children in New York. Her position at the New England Hospital for Women and Children impressed her with the need for preventive pediatrics and initiated her passion to capture and write about “the natural history of the child.” Ilg also worked at Bellevue Hospital  in  New York  City  and  was  a  child  health worker in Stockholm. She adopted her daughter, Tordis Kristen, as a single parent, unusual in 1936. She wrote that her years of looking at child behavior closely mirrored her daughter’s developmental stages.

Ilg  started  her  work  and  collaboration  with Dr. Arnold Gesell at the Yale Clinic for Child Development. Together, using the guidance nursery, clinical examination  suite,  and  photographic  processes,  Ilg and Gesell coauthored Feeding Behavior of Infants. This was the first of more than 30 collaborative works to be authored and coauthored through the work of the Yale University initiated school of child development, the first in the United States. The study of maturation, showing a pattern of similar growth and benchmarks for youngsters, ran counter to the prevailing paradigm. Her work not only targeted the physical aspects of children, but also the social, emotional, and intellectual growth patterns. As thousands of children were seen at the clinic, careful scientific databases were collected, including rich cinematic records and meticulous observations of children to validate the findings. Parents and records of family interactions were also included. The collaborative nature of her work continued with Dr. Louise Ames and Dr. Janet Rodell as Ilg and the team recognized, investigated, and expounded on the biological timetable functioning in conjunction with the surrounding social milieu. As a maturationist, Ilg also authored the Gesell Developmental Assessment Manual in 1965. She wrote the widely syndicated daily column, “Child Behavior” for many years.

In collaboration with Gesell, the world-renowned trilogy exploring youth and development was written, including Gesell Institute’s Child from One to Six, The Child from Five to Ten, and The Years from Ten to Sixteen. This material is still available at local bookstores and referenced in child development literature as well as popular writing.


  1. Ames, , Ilg, F., & Haber, C. (1982). Your one-year-old: The fun-loving, fussy 12to 24-month-old. New York: Dell.
  2. Ames, L. & Ilg, F. (1979). Your six-year-old: Loving and def New York, NY: Dell.
  3. Gesell, , & Ilg, F. L. (1937). Feeding behavior of infants: A pediatric approach to the mental hygiene of early life. Philadelphia: JB Lippincott.
  4. Gesell Institute of Human Development,