Clark University, in Worcester, Massachusetts in the United States, is a private teaching and research institution founded in 1887. Clark is the second oldest graduate institution in the United States and the oldest graduate institution in New England. Clark is one of only three New England universities, with Harvard and Yale, to be a founding member of the prestigious Association of American Universities. Clark withdrew membership from the Association of American Universities in the late 1990s.

Clark's first president was G. Stanley Hall, founder of the American Psychological Association, who earned the first Ph.D. in psychology in this country at Harvard. Clark has played a prominent role in the development of psychology as a distinguished discipline in the United States. Clark was the location for Sigmund Freud's famous "Clark Lectures" in 1909, introducing psychoanalysis to this country. Clark was also associated, in the 1920's, with Robert Goddard, a pioneer of rocketry, considered one of the founders of space and missile technology.

In recent years, Clark has been noted especially for its geography and psychology departments, with the latter having a distinctive, if increasingly unfashionable "humanistic" orientation (humanistic psychology). Clark's geography department is best known for its strength in human-environment geography and for the development of the Idrisi [geographic information systems] software.

Located in an industrial, residential neighborhood ("Main South") of the New England mill town of Worcester, Clark benefitted for many years from the patronage of the wealthy factory owner families in the town, who saw the numerous colleges in their city as a cultural endowment that might lift the factory-working population of the city to a more sophisticated level.

Clark has flourished, marketing its programs off campus and accepting a student body largely from out of the city and often from out of the state.