 Carter was Executive Director of the Washington Urban League in the mid-1950s, and later worked for the National Urban League in New York.He entered government as a Deputy Assistant Secretary at the U.S. Department of Health, Education and Welfare under the Kennedy Administration.He later became an Assistant Director of the Office of Economic Opportunity, and then became Assistant Secretary of HEW under the Johnson Administration, becoming one of the highest-ranking African Americans in that department before leaving in 1968.