Frances L. Ilg

Frances Lillian Ilg, M.D. (1902–1981) was an American pediatrician, child-development specialist, and professor at Yale University. She earned her medical degree from Cornell Medical School in 1929 and was associated with Yale’s Clinic of Child Development from 1932 to 1950, later serving as an assistant professor of child development. In 1950, she co-founded the Gesell Institute of Child Development in New Haven with Louise Bates Ames and Janet Learned.

Ilg co-authored numerous works on infant and child development, including The Child from Five to Ten, Child Behavior, and the widely known series Your One-Year-Old, Your Two-Year-Old, Your Three-Year-Old, Your Four-Year-Old, and Your Five-Year-Old. She died in 1981.