Correspondence, memoranda, subject and project files, speeches and writings, transcripts of interviews and testimony, book drafts, minutes, reports, administrative, academic, and financial records, printed matter, and secondary background material. The bulk of the collection (1935-1990) relates to Clark's career as a psychologist and professor at the City College of New York, his contributions to the African American civil rights movement and equal educational opportunities, and his various consulting firms, especially Metropolitan Applied Research Center, a group he organized in New York, N.Y., to advocate for the urban poor and disadvantaged. Topics include the psychological effects of racial discrimination and segregation, school integration, Brown v. Board of Education of Topeka, riots in Harlem, New York, N.Y., the integration of public schools in Little Rock, Ark., and the work of psychologist Otto Klineberg.

Clark's work with his wife, child psychologist Mamie Phipps Clark, with whom he founded the Northside Center for Child Development, New York, N.Y., is also documented. Other affiliations represented include Harlem Youth Opportunities Unlimited (HARYOU), Intergroup Committee on New York's Public Schools, Mid-Century White House Conference on Children and Youth, National Association for the Advancement of Colored People, National Child Labor Committee, National Scholarship Service and Fund for Negro Students, Society for the Psychological Study of Social Issues. Also includes records of the Central Division, Brooklyn , N.Y., of Marcus Garvey's Universal Negro Improvement Association (1922-1962). Correspondents include Gordon W. Allport, Hubert T. Delany, Alfred Lee McClung, Gardner Murphy, A. Philip Randolph, Louis L. Redding, and Elizabeth Waring.