<p>How do Muslim citizens respond to immigrants who hold fundamentalist interpretations of Islam? Although the social science literature has examined public perceptions of Muslim fundamentalists, it has primarily focused on Western liberal democracies. Consequently, we know relatively little about how Muslim citizens in Muslim-majority societies evaluate immigrants with extreme religious beliefs. To address this gap, this paper provides empirical evidence on how Muslim nationals assess immigrants based on variations in religion and religious intensity. We conducted a conjoint experiment in Kazakhstan, a secular state with a Muslim-majority population, in which respondents evaluated profiles of hypothetical immigrants with randomly assigned characteristics. The results show that Muslim citizens express unfavorable attitudes toward fundamentalist Muslim immigrants. Moreover, more religious respondents are even more likely to disapprove of such immigrants. These findings suggest that Muslim citizens do not simply draw social boundaries based on shared religious affiliation. Rather, they distinguish between in-group and out-group members according to competing interpretations of what constitutes “Islam.” Higher levels of religiosity therefore do not necessarily translate into greater support for fundamentalist beliefs.</p>