This paper shows that poor households’ entitlement to an exogenous, temporary, but guaranteed income stream increases Mexican migration to the United States, although this income is mainly consumed. Some households use the entitlement to this income stream as collateral to finance the migration. The new migrations come from previously constrained individuals and households and worsen migrant skills. In sum, financial constraints to international migration are binding for poor Mexicans, some of whom would like to migrate but cannot afford to. As growth and antipoverty and microfinance programs relax financial constraints for the poor, low-skilled Mexican migration to the United States will likely increase.