Ruth O'Dell Cox, 63, a former Arlington School Board member and speech therapist died Wednesday at Arlington Hospital of congestive heart failure.

Mrs. Cox began teaching in the Arlington school system during the 1940s. She then moved to George Washington University, where she taught speech and continuing education for women until her retirement last spring.

She was born in Cornwall, N.Y., and earned a bachelor's degree in speech from Syracuse University in 1936. In 1962, she earned a master's degree in speech from George Washington University.

Mrs. Cox, who moved to this area around 1940, served on the Arlington School Board from 1962 to 1970. She also was a member and officer of the Virginia State School Boards Association.

She served two terms as president of the Arlington branch of the American Association of University Women and was a past president of the Arlington Civic Federation. In 1963, she received that organization's Evening Star trophy for service to the community.

Survivors include her husband, Robert W., of the home in Arlington; two sons, Robert A., of Bedford, Tex., and Kevin C., of Arlington, and seven grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the Hospice of Northern Virginia, P.O. Box 1590. Arlington, 22210.