Robert W. Scrivner, the director of the Rockefeller Family Fund, died of cancer at his home in Cos Cob, Connecticut. He was 48 years old. Mr. Scrivner had played an influential role in stimulating interest among philanthropies in supporting research and programs aimed at preventing nuclear war and promoting arms control and resolution of disputes. Mr. Scrivner was also secretary of the Rockefeller Family Fund, a grant- making institution set up in 1967 to serve as the major channel for the philanthropic interests of the younger members of the Rockefeller family. He helped shape the foundation's program areas, which included arms control, conservation, the women's movement and public-interest activities. He was elected director in 1972. He was born in Kansas City, Mo., was educated at Harvard College and won a fellowship for a year's study at Emmanuel College, Cambridge University. He received a law degree from Harvard's School of Law in 1961 and went on to practice law in Pittsburgh. In 1963, he joined the Rockefeller Brothers Fund, the philanthropy created by the five sons of John D. Rockefeller Jr., later joined by their sister. He was a trustee of the American Friends of Cambridge and also the New York Regional Association of Grantmakers. He is survived by his wife, the former Melinda Brown; a daughter, Katherine; his mother, Mrs. George R. Scrivner of Topeka, Kan., and a brother, Noel C. Scrivner of Wilmington, Del.