Through a sociological, ethnographic study of two churches founded by Ghanaian Pentecostals in Chicago, this dissertation analyzes how immigrants' religion facilitates inter-ethnic contact. Specifically, it examines the role of evangelism in assimilation by asking three central questions: what behaviors enable and constrain immigrants in their attempts to create non-ethnic congregations? To what extent are members from other ethnic groups integrated into these new congregations? And, how does engaging in inter-ethnic evangelism shape immigrants' understanding of themselves and the United States? This project contributes to the literature on religion and immigration in America in several ways. First it moves beyond the ethnic church as the paradigm for understanding immigrant religious behavior by developing the concept of immigrant missionaries. This new framework highlights the role and importance of non-ethnic identities and interests in immigrant congregations. In addition, this dissertation seeks to further our understanding of the relationship between religion and assimilation for immigrants. I argue that a strong ethos of evangelism combined with extensive management of church members' ethnic displays, encourages reverse assimilation. In this process, immigrants become members of diverse religious organizations not by joining American congregations, but by having native born Americans and other immigrants join their institutions. Finally, by exploring the case of Ghanaian Christianity in the United States, this dissertation remedies the empirical neglect of African immigration and explores its implications for the changing face of American Christianity.