Dorothy V. Thomas, 76, retired casework director of the Family and Child Services of Washington, died of cancer Monday at Sibley Memorial Hospital.

She had retired in 1967 after 24 years with the agency.

Born in Trenton, Neb., Miss Thomas was a graduate of the University of Nebraska, where she also earned two master of arts degrees in sociology. She received a third master's degree YWCA secretary at the University of Chicago's School of Social Services.

Before coming here, she had been YWCA secretary of the University of Oregon, supervisor at Juvenile Court in Chicago, and supervisor of the Emergency Relif Administration in Chicago.

After coming here, Miss Thomas was a psychiatric social worker at St. Elizabeths Hospital until joining Family and Child Services.

She had taught at numerous institutes and seminars on both the East and West coasts sponsored by the Family Service Association of America. She also had written articles for a number of professional journals.

Miss Thomas, who lived in Washington, was a member of the National Association of Social Workers and the Academy of Certified Social Workers.

She is survived by two brothers, Morton F. Thomas, of Roswell, N.M., and the Rev. Howard L. Thomas, of Azusa, Calif.

The family suggests that expressions of sympathy may be in the form of contributions to the American Cancer Society or Family and Child Services.