Ralph Aubrey Young, 78, a retired senior adviser to the Federal Reserve System's Board of Governors and a top government economist in the 1940s and 1950s, died of a respiratory ailment Wednesday at his Washington home.

From the mid-1940s, when he joined the Federal Reserve, until the end of the Eisenhower administration, Mr. Young was one of three Federal Reserve advisers -- the others were Winfield Riefler and Woodlief Thomas -- who helped shape this country's economic policies.

Mr. Young was appointed assistant director of the Federal Reserve Board of Governors' division of research and statistics in 1946. Before that, he had directed the financial research program of the National Bureau of Economic Research and for many years was on the faculty of the Wharton School of Commerce and Finance of the University of Pennsylvania. He also was chairman of the Wharton School's economics department. He earned a doctorate from the University of Pennsylvania in 1930.

He became director of the Federal Reserve Board's division of research and statistics in 1949, and held that position until 1960, when he was appointed adviser to the board and elected secretary of the Federal Open Market Committee, one of the five divisions of the Federal Reserve System. mHe remained an adviser until 1966.

Mr. Young also served as director of the board's division of international finance from 1961 until 1965. In this capacity, he represented the board at meetings of the economic policy committee of the Organization for Economic Cooperation and Development and participated in numerous international economic and monetary conferences.

After retiring in 1967, Mr. Young was a consultant to the International Monetary Fund's central banking service until 1975.

He was born in Cheyenne, Wyo. He earned bachelor's and law degrees from Ohio Weslyan University and a master's degree from Northwestern University.

He held numerous professional memberships and wrote many books on banking and finance, including "Monetary Instruments in the United States: Role of the Federal Reserve System."

Mr. Young lived in Washington. He was a member of the Cosmos Club and attended Metropolitan Memorial United Methodist Church here.

Survivors include his wife of 44 years, the former Louise Merwin, of Washington; two sons, Merwin C., of Madison, Wis., and Ralph A. Jr., of Manchester, England; a daughter, Anne Alexandra Pierce of Redlands, Calif.; a brother, Paul H., of St. Louis; a sister, Jessie West of Portland, Ore., and seven grandchildren.

The family suggests that expressions of sympathy in his name be made to the Alumni Endowment Fund at Ohio Wesleyan University, Delaware, Ohio 43015.