Harold Lasswell, in full Harold Dwight Lasswell, (born February 13, 1902, Donnellson, Illinois, U.S.—died December 18, 1978, New York, New York), influential political scientist known for seminal studies of power relations and of personality and politics and for other major contributions to contemporary behavioral political science. He authored more than 30 books and 250 scholarly articles on diverse subjects, including international relations, psychoanalysis, and legal education.

Lasswell received his bachelor’s degree in philosophy and economics in 1922 and his Ph.D. in 1926 from the University of Chicago, and he studied at the Universities of London, Geneva, Paris, and Berlin during several summers in the 1920s. He taught political science at the University of Chicago (1922–38) and then served at the Washington School of Psychiatry (1938–39) and was director of war communications research at the U.S. Library of Congress (1939–45). After World War II, he went to Yale University, where he served until the 1970s in various capacities, including as professor of law, professor of political science, and Ford Foundation Professor of Law and Social Sciences and emeritus fellow of Bramford College. He was also a professor of law at John Jay College of the City University of New York and at Temple University. He was a visiting lecturer at campuses throughout the world and was a consultant to numerous U.S. government agencies.

Lasswell viewed political science as the study of changes in the distribution of value patterns in society, and, because distribution depends on power, the focal point of his analysis was power dynamics. He defined values as desired goals and power as the ability to participate in decisions, and he conceived political power as the ability to produce intended effects on other people. In Politics: Who Gets What, When, How (1936)—a work whose title later served as the standard lay definition of politics—he viewed the elite as the primary holders of power, but in Power and Society: A Framework for Political Inquiry (1950), written with Abraham Kaplan, the discussion was broadened to include a general framework for political inquiry that examined key analytic categories such as person, personality, group, and culture.

His works on political psychology include Psychopathology and Politics (1930), which seeks the means of channeling the desire for domination to healthy ends; World Politics and Personal Insecurity (1935); and Power and Personality (1948), which deals with the problem of power seekers who sublimate their personal frustrations in power. In these and later works, Lasswell moved toward a moralistic posture, calling for the social and biological sciences to reorient themselves toward a science of social policy that would serve the democratic will for justice. Other features of political science that can be traced to Lasswell include systems theory, functional and role analysis, and content analysis.

Some of his other major works include Propaganda Technique in the World War (1927), World Revolutionary Propaganda (with Dorothy Blumenstock, 1939), Politics Faces Economics (1946), The Policy Sciences: Recent Developments in Scope and Method (with Daniel Lerner, 1951), and The Future of Political Science (1963).