Dr. Orville John McDiarmid, 73, a retired chief economist at the World Bank and the chairman of the Industrial Development Authority of Falls Church since about 1980, died of a pulmonary embolism Dec. 19 at Georgetown University Hospital. He lived in Falls Church.

Dr. McDiarmid, who had lived in the Washington area since 1942, was a native of Ottawa, Canada. He was a graduate of the University of Ontario and earned his doctorate at Harvard University. Before World War II, he taught economics at the old Carnegie Institute of Technology in Pittsburgh and at the College of William and Mary.

During the war, he served in the Army in the Southwest Pacific. He then spent a year as an economics officer with occupation forces in Japan. He worked for the State Department from 1946 to 1955, where he became chief of the international finance division and was deputy director a development mission in the Philippines.

Dr. McDiarmid joined the World Bank in 1955, where his work included development projects dealing with the Middle East and Far East. He retired in 1974. He was the author of a World Bank report on development in Kuwait and two books on economics.

Survivors include his wife, Dr. Alice Morrissey McDiarmid of Falls Church; a daughter, Marjorie McDiarmid of Arlington; a son, John, of Erie, Pa.; a brother, Fergus J., of Naples, Fla., and a sister, Marjorie Kempner of New York City.