The study of the relationship between the anglophone and Islamic worlds in the seventeenth century has been the subject of increas- ing interest in recent years, and much attention has been given to the cultural anxiety surrounding “Turning Turke”, conversion from Christianity to Islam, especially by English captives on the Barbary coast. Conversion in the other direction has attracted far less scrutiny, not least because it appears to have been far less com- mon. Conversion from Islam to any form of radical dissent has attracted no scholarship whatsoever, probably because it has been assumed to be non-existent. However, the case of Bartholomew Cole provides evidence that such conversions did take place, and examining the life of this “Turke turn’d Quaker” provides an insight into the dynamics of cross-cultural conversion of an exceptional kind.