Abstract: | Rapid urbanization is among the major processes affecting the developing world. The influx of migrants to cities frequently provokes antagonism on the part of long‐term residents, manifested in labor market discrimination, political nativism, and violence. We implemented a novel, face‐to‐face survey experiment on a representative sample of Mumbai's population to elucidate the causes of anti‐migrant hostility. Our findings point to the centrality of material self‐interest in the formation of native attitudes. Dominant group members fail to heed migrants' ethnic attributes, yet for minority group respondents, considerations of ethnicity and economic threat crosscut. We introduce a new political mechanism to explain this divergence. Minority communities facing persistent discrimination view in‐migration by coethnics as a means of enlarging their demographic and electoral base, thereby achieving “safety in numbers.” Our article sheds light on the drivers of preferences over internal migration. It also contributes insights to the international immigration literature and to policy debates over urban expansion. |