Joseph Sweeney, 66, a retired Foreign Service officer, died of cancer Wednesday at his home in Sumner, Md.

Mr. Sweeney was born in Salem, Mass., and grew up there and in the Los Angeles area. He earned a bachelor's degree from Whittier College and a master's degree in social work from the University of Southern California. He was a social worker in the Los Angeles area and then went to the Fletcher School of Law and Diplomacy at Tufts University, where he earned master's and doctoral degrees.

During World War ii, he worked briefly for the American Red Cross and then joined the old Office of Strategic Services. He began his State Department career in 1945 as chief of the British Commonwealth bureau in the department's office of research and intelligence. He held that position from 1945 to 1950.

Subsequent assignments took him to South Africa, the Sudan, Sweden, Saudi Arabia and the United Nations. He returned to the State Department as officer in charge of the United Kingdom and Ireland desk and then was deputy chief of mission at the U.S. Embassy in Dublin, Ireland, in 1963 and 1964. He taught at the Armed Forces Staff College in Norfolk, Va., from 1964 to 1966. He was on the board of examiners of the Foreign Service in the State Department from 1966 until his retirement in 1968.

Mr. Sweeney taught international relations and Africa history at York College in York, Pa., after leaving the government. He had maintained a residence in the Washington area since 1959.

Survivors include his wife, Adelaide Rasin Sweeney, of the home; a son, Kevin, of Middletown, Pa., a daughter, Ellen S. Cline, of Los Angeles, and a brother, Francis, of Manhattan Beach, Calif.