To include a chapter on deconversion in a handbook on conversion is not only appropriate, but, as I argue, necessary for various reasons: It is no longer possible to ignore the fact that a growing number of contemporaries chose to convert more than once in their lifetime; multiple conversions are unavoidable in cultures in which religion occurs no longer as singular in a mono-religious environment, but as plural. Multiple conversions, however, involve deconversion(s). While some contributions use the term “conversion” for both the disaffiliation and the re-affiliation, I focus on “deconversion” in order to include disaffiliations without re-affiliation – which responds to the growing attention to atheists and apostates in the US (cf. Streib & Klein, 2011). Disaffiliation processes constitute an independent field of study that deserves special scientific attention. And here, the term “deconversion” may serve as a reminder of the depth and intensity of biographical change and the new orientation of one’s life that eventually is associated with disaffiliation and is not reserved to conversion. In this chapter, I will start with a conceptualization of deconversion, discuss recent quantitative and qualitative research, and finally draw conclusions and suggest directions for future research.