Data from the first post-Arab Spring elections reveal that support for Islamic parties came from richer districts and individuals. We show that standard public finance arguments help explain the voting pattern in these elections and others in the Muslim world. Our model predicts that a voter’s probability to vote for a religious party (i) increases in income for the poorest voters, but possibly decreases in income for the richest; (ii) is greater for voters in richer districts; and (iii) increases with the voter’s religiosity. We test these predictions on original micro-level data in a nationally representative sample of 600 individuals in 30 districts in Tunisia. Our empirical results align with our predictions and suggest that belonging to the middle class and living in a richer district together affect voting decisions more than being a religious voter. We also test for other possible factors affecting voting decisions, such as education, or attitudes towards corruption or towards the West. Finally, we document similar patterns in other key elections in the Muslim world.