Categories that become taken-for-granted tend to acquire rule-like standing. That is, people begin to strongly expect certain behaviors from entities that have claimed affiliation with them, and these expectations tend to induce conformity. However, conformity does not always ensue, and we lack an explanation of why the effects of category taken-for-grantedness might diverge. In this paper, we propose that the effects of increasing category taken-for-grantedness hinge upon an organization’s identity. We first argue that the relationship between organizational identity and the likelihood of conformity is U-shaped, with insiders and outsiders being more likely to conform relative to those with middling identities. We then propose that greater category taken-for-grantedness should reduce scrutiny for those whose identities mark them as more of insiders, subsequently making them less likely to conform. In contrast, outsiders become more likely to conform as taken-for-grantedness increases. We test our arguments in the empirical context of Islamic banking, using data on 118 Islamic banks worldwide between 2001 and 2014. We examine the likelihood that banks in the sector make what are known as zakat payments as a function of category taken-for-grantedness and the extent to which a bank’s identity is Islamic. We discuss implications for the literatures on categories, identity, and religion.