This chapter reviews the theoretical framework for the study of immigration and ethnicity. It addresses the issues of transnationalism, immigration, and the reconstruction of ethnic identities, multiculturalism, tribalism, and tribal identities. One of the crucial issues at the center of the study of contemporary immigrant flows has to do with the immigrants’ ethnic identity and cultural orientation. Ethnic formation among immigrants is a dynamic process, one which is not only determined by primordial and cultural factors but also by instrumental needs of immigrants. One of the main reasons for the rise of multiculturalism is connected to the global labor migration, which brought many challenges to receiving countries. The concept of modern tribal societies originates in the work of the French social theorist Michel Maffesoli. Maffesoli adopts the perspective of Durkheim and his followers, who placed the greatest weight on the “sacredness of social relationships”.