White spent most of the next decade in St. Mary's City, working on English-Native American relations, particularly with the Yaocomico tribe, which consistently saw favorable trade treaties from Calvert because of White, and the Anacostans. In 1637 they were joined by fellow Jesuits Thomas Copley and Ferdinand Poulton, and between 1634 and 1650 there averaged four permanent Jesuits in the Maryland Provincial Colony. To further his missionary work, he wrote dictionaries and translated the catechism into the native languages. On July 5, 1640, he famously converted Chitomachon, the chief of the Piscataway Indians, to Christianity. The chief was baptized as Charles. He later baptized a princess of the Patuxent Indians, and much of her tribe.