Reginald was born around 1183 in Saint-Gilles, Languedoc, to a French Catholic family. Educated in canon law, he became Dean of the cathedral chapter of Saint-Aignan at Orléans and professor of canon law at the University of Paris — distinguished as one of the principal canon-lawyers of the early-13th-century French Catholic academy.
In 1218, on the pilgrimage to Rome, Reginald first met St. Dominic de Guzmán — the founder of the Order of Preachers (Dominicans, papally recognized in December 1216). Captivated by Dominic's apostolic vision, Reginald sought admission to the new Order.
Reginald was afflicted with a severe illness that his physicians deemed fatal — until, per the classic Dominican hagiographical tradition preserved in the Vitae Fratrum of Bl. Gerard de Frachet, the Blessed Virgin Mary appeared to Reginald in a vision and anointed him with miraculous oil, curing him.
In the same vision, the Blessed Virgin revealed to Reginald the Dominican scapular (the white-scapular vestment component of the Dominican habit) — showing him the precise form of the garment. The vision became one of the principal Marian-devotional narratives of the Dominican Order, analogous to the Carmelite-scapular vision of St. Simon Stock (1251).
After his miraculous cure, Reginald entered the Dominican Order in Rome under Dominic's direct reception. Dominic sent him to Bologna to preach and to establish the Dominican community there — producing the famous burst of Bolognese Dominican vocations under Reginald's charismatic preaching (including the future Bl. Jordan of Saxony, Dominic's successor as Master of the Order).
In 1219 Reginald was sent to Paris to establish the Dominican convent of Saint-Jacques — the principal French Dominican foundation, which would become the principal centre of the Order at the University of Paris (producing Sts. Thomas Aquinas, Albert the Great, and the entire Dominican-scholastic tradition). Reginald died at Saint-Jacques in Paris on February 1, 1220 — the first Dominican to die at the Paris foundation.