Edward Lewis Deci (/ˈdiːsi/; (October 14, 1942 – February 14, 2026) was an American academic and psychologist who was Professor of Psychology and Gowen Professor in the Social Sciences at the University of Rochester, and director of its Human Motivation Program. He was well known in psychology for his theories of intrinsic and extrinsic motivation and basic psychological needs which he had been researching for 40 years. With Richard Ryan, he was the co-founder of self-determination theory (SDT), an influential contemporary motivational theory.

Deci was also president and director of the Monhegan Museum in Monhegan, Maine.

Edward Lenris Deci was born in Palmyra, New York, on October 14, 1942. He attended Hamilton College in Clinton, New York. Deci graduated in 1964 with a degree in mathematics. He then studied at the Wharton School of the University of Pennsylvania and earned his Master of Business Administration from there in 1967.

He went on to earn his PhD from Carnegie Mellon University in social psychology in 1970. In his dissertation, he explored intrinsic motivation and the way social-contextual factors may have an effect on motivation.

Self-determination theory is a macro theory of human motivation that differentiates between autonomous and controlled forms of motivation; the theory has been applied to predict behavior and inform behavior change in many contexts including: education, health care, work organizations, parenting, and sport (as well as many others).

Deci died of complications from dementia in Rochester, New York, on February 14, 2026, at the age of 83.