William Baum was born Nov. 21, 1926, in Dallas, Texas. He moved to Kansas City, Missouri, at an early age, and there entered St. John´s Minor Seminary at 13. He was ordained a priest on May 12, 1951.
In 1970, Paul VI appointed him bishop of Springfield-Cape Girardeau, Missouri. In March 1976, he was named archbishop of Washington, D.C.; that May he was made a cardinal.
He was prefect of the Congregation for Catholic Education from 1980 until 1990. In April 1990, he was named major penitentiary by John Paul II.