James Michael Regan was born in Bradford, Connecticut, on May 21, 1896, and received his early education at primary and secondary public schools in New Haven. Following his father's death in 1913, he worked for two years to help support his family before taking up college studies at Aquinas College in Columbus, Ohio. In 1917, he entered the Dominican novitiate at St. Joseph's Priory in Somerset, Ohio, and made first profession there on August 5, 1918.

Shortly after beginning his philosophical studies at St. Rose Priory in Springfield, Kentucky, Brother Joseph Regan developed a serious tubercular condition arid was sent to St. Dominic's in Denver. Colorado, to continue his formation. In 1922, he went to Washington, D.C., for additional theological studies, but, before long, his health began to fail again. He was ordained a year early on June 18, 1924, and immediately sent back to Denver.

Father Regan served first as associate pastor and then as pastor in Denver until 1940. From 1940 to 1948, he worked to establish a new foundation at Blessed Martin Mission in Amarillo, Texas. From 1948 to 1966, he served as pastor in Canton, South Dakota; Mangum, Oklahoma; and Boyce, Louisiana.

In 1967, Father Regan returned to Denver as an associate pastor. By 1974, chronic cardiac difficulties indicated a change in altitude was in order, and he moved to New Haven, Connecticut, where he lived in retirement with his sister near St. Mary's Priory until the time of his death on January 3, 1976. Following services at St. Mary's Church, he was buried in the Dominican plot in New Haven.