--- - |2 A substantial scholarship has studied the extent to which states across the political and geographic spectrums rely on legal, bureaucratic, and judicial institutions to govern religion. However, a deeper inquiry into the mechanisms through which regulation occurs has yet been achieved. This article foregrounds conversion, understood as mobility between social groups in which belief and sincerity may figure but is not reducible to either, to observe these dynamics. Through an analysis of Egyptian jurisprudence on the right to change religion as well as interviews with complainants and litigators, the article challenges widespread assumptions about who and what constitute the regulatory field. It also shows how religious difference is produced in the legal‐bureaucratic encounter. By accounting for institutions that are not typically considered part of the regulatory field nor thought to be bound by the strictures of legal positivism, this article further occasions a rethinking of the public–private distinction within critiques of secularism. - 'Law &Society Review, Volume 52, Issue 3, Page 574-602, September 2018. '