This article offers an in-depth examination of Sir Tobie Matthew’s conversion as an attempt to understand not only the internal process of conversion for one individual, but also its meaning for the English Catholic community during the early seventeenth-century. Matthew was an extraordinary figure. He was both learned and extremely well-connected, with friends in the highest echelons of the Roman Catholic Church, and in English society, and this despite his conversion. He maintained those relationships to his benefit throughout his life. Officially he was at times an exile from England and at other times at court, nonetheless he was always at the centre of dynastic politics. He maintained loyalty to England throughout his life, but clearly felt a draw to Catholicism for its intellectual tradition, emotional appeal, his desire to travel; and, perhaps, also for reasons of sexuality. Sir Tobie’s conversion reveals just how complex the relationship between religious and national identity could be after the Reformations.