In 1993, he moved on to the Pontifical North American College in Rome, where he gained a licentiate in theology at the Pontifical Gregorian University.
Toups was ordained to the priesthood June 14, 1997, for the Diocese of St. Petersburg and appointed parochial vicar of St. Frances X. Cabrini Parish in Spring Hill, Florida. He then studied for a doctorate in theology at the Pontifical University of St. Thomas Aquinas (the Angelicum), writing his thesis on "The Sacerdotal Character as the Foundation of the Priestly Life: The Contribution of Blessed Columba Marmion."
From 2004 to 2006, he was professor of sacramental and liturgical theology, as well as dean of students, at St. Vincent de Paul Regional Seminary.
In 2007, he was released from diocesan assignment to serve as associate director of the Secretariat for Clergy, Consecrated Life, and Vocations at the U.S. Conference of Catholic Bishops in Washington.
In 2010, he returned to St. Petersburg diocese, where he was pastor of Christ the King Parish in Tampa for two years before being named president and rector of St. Vincent de Paul Regional Seminary.
Guillory, a member of the Society of the Divine Word, became the fifth bishop of Beaumont on July 28, 2000. He was the first member of a religious order to lead the diocese and the first African American ordinary in Texas, according to a biography on the diocese's website.