羅榮
After studying in the United States, Mẫn taught in Vietnam for a number of years. In 1993, he was appointed Coadjutor Bishop of Mỹ Tho and promoted to Archbishop of Hồ Chí Minh City in 1998. He officiated at a mass in La Vang in 1998 for the 200th anniversary of the apparition of the Virgin Mary, the largest Vietnamese Catholic event up to that time.