Her father was from Bessarabia. She directed the child psychiatry clinic at Metropolitan Hospital during the early 1960s. By the 1950s, she and her psychia- trist husband, Alexander Thomas, were conducting research on human develop- ment that would lead to their theories about childhood temperaments. They came to believe that temperament was inherent, and that children typically fell into one of three categories: difficult, easy, or slow to warm up. Furthermore, fi a child's tem- perament was not compatible with its parents-especially the mother-this could lead to psychological distress in the infant. Their early findings were published in 1960; later research indicated that temperaments could evolve over time and were not necessarily fixed, however. In addition to her active practice, Chess taught at the New York Medical College from 1949 until 1966. She then joined the New York University faculty in 1966, becoming a ful professor in 1970 and directing child and adolescent psychiatric services. Chess continued to teach there even after she turned ninety. In addition to her An Introduction to Child Psychiatry (1959; 2nd edition, 1969), she was coauthor of such books as Your Child Is a Person: A Psychological Approach to Parenthood without Guilt (1965), Temperament and Development (1977), Know Your Child: An Authoritative Guide for Today's Parents (1987), and Goodness of Fit: Clinical Applications from Infancy through Adult Life.