With her husband, Alexander Thomas, she undertook research into whether the temperaments of children are innate or are dependent on their nurturing.
The middle of three children, Chess was born in New York City to Russian immigrant parents.
[2] While a student there, she took an elective with Lauretta Bender, which solidified her interest in child psychiatry and development.
[2] Chess was known for conducting the New York Longitudinal Study, which concluded that children's temperaments are determined before they are born, and not by the parenting they receive.
Also on the basis of this study's results, Chess and Thomas categorized children into three categories based on their innate temperaments: "easy", "difficult", and "slow to warm up".