Religion plays multifaceted roles on both sides of the US-Mexico border. Mexican immigrants and US Catholic institutions have both crossed this border, and in the process have utilized and shaped religion in contradictory ways. Drawing on archival research, this study examines the intersections of religion, migration and race in the two decades following the start of the Mexican Revolution. I examine the movement of Mexicans to Chicago as part of a mass exodus of Mexicans to the US in response to the Revolution, with particular attention to their religious needs and practices. The Catholic Church Extension Society, based in Chicago, was also focused on Mexican Catholicism during this time. The Extension Society provided financial support to Mexican priests, and lobbied in Washington, Mexico City and the Vatican on behalf of Mexican Catholics. I examine both of these phenomena through a binational lens, examining the ways US imperial interests and Catholic colonial interests in Mexico competed with and supported each other. By looking at the experiences of Mexican Catholics in Chicago and the work of the Extension Society in Mexico and the US, I provide insights into the transnational context of cultural contact and resulting immigrant flows.