This chapter introduces the subject of conversion by considering issues, themes, theories, and methods in the study of Christian conversion. Conversion is movement from something to something. Its process is dynamic and multifaceted and raises a number of questions: Is the change intellectual, social, psychological, moral, or some combination? Is it an event or a process? Who defines conversion—the scholar, the religious community, the convert? Examining conversion over two millennia of Christian history complicates matters even more, for the meaning of the word and the concept itself varies from person to person, from group to group, and from setting to setting. This chapter examines various theoretical models of conversion (Lewis Rambo’s seven stages, the “conversion motifs” of John Lofland and Norman Skonovd, Henri Gooren’s “conversion career,” and others) and applies these models to a single conversion narrative. The chapter concludes by highlighting a number of broad themes found in the chapters ahead.