He entered the Salvatorian Seminary in Street Nazianz, and then studied philosophy at Loras College/Saint Pius X Seminary in Dubuque, and Theology at the Pontifical North American College and Pontifical Gregorian University in Rome.
He is the seventh and current bishop of Bismarck. He received the primary education at Saint Peter School in Spring Grove. He followed to obtain licenciate in Canon Law at the Gregoriana (1977–1979).
He was ordained priest on June 14, 1975 in the Diocese of Rockford.
He served as president of the Presbyterial Council, and editor of the Diocesan weekly paper. In 1994, Kagan was named Vicar General and Moderator of Curia, as well as Honorary Prelate.
In 2011 he was promoted to Protonotary Apostolic. Kagan was named bishop of Bismarck on October 19, 2011, following the retirement of Bishop Zipfel, 77, after a ministry of fourteen years.
He was consecrated and installed as bishop at Bismarck"s Cathedral of the Holy Spirit on Wednesday, November 30, 2011.
Archbishop John Clayton Nienstedt of the Roman Catholic Archdiocese of Saint Paul and Minneapolis (who, as such, is the Metropolitan Archbishop of the ecclesiastical province that the Diocese of Bismarck is a part of) was the principal consecrator. Bismarck"s Bishop Emeritus Zipfel and Bishop Thomas G. Doran of the Roman Catholic Diocese of Rockford, Illinois, were the principal co-consecrators. This was the first episcopal consecration at which Archbishop Carlo Maria Vigano represented Pope Benedict XVI in his official capacity as Apostolic Nuncio to the United States.
Member of Catholic Theological Society of America, Canon Law Science American (associate).