George A. Hanus was born in Brainard, Nebraska. He took the name Jerome when he entered Conception Abbey, in Conception, Missouri. On September 1, 1961, he professed religious vows in the Order of Saint Benedict. He was educated at Conception Seminary and ordained a priest on July 30, 1966.
He was sent for advanced studies at St. Anselm University in Rome and Princeton Theological Seminary in the Borough of Princeton, New Jersey. He served as a professor at Conception Seminary. On January 5, 1977 he was elected the sixth Abbot of Conception Abbey, and he received the abbatial blessing the next day. From 1984-87 he served as President of the Swiss American Benedictine Congregation.