Major paradigms in immigration research, including assimilation theory, multiculturalism, and ethnic studies, take it for granted that dividing society into ethnic groups is analytically and empirically meaningful because each of these groups is characterized by a specific culture, dense networks of solidarity, and shared identity. Three major revisions of this perspective have been proposed in the comparative ethnicity literature over the past decades, leading to a renewed concern with the emergence and transformation of ethnic boundaries. In immigration research, "assimilation" and (...) u integration" have been reconceived as potentially reversible, powerdriven processes of boundary shifting. After a synthetic summary of the major theoretical propositions of this emerging paradigm, I offer suggestions on how to bring it to fruition in future empirical research. First, major mechanisms and factors influencing the dynamics of ethnic boundary -making are specified, emphasizing the need to disentangle them from other dynamics unrelated to ethnicity. I then discuss a series of promising research designs, most based on nonethnic units of observation and analysis, that allow for a better understanding of these mechanisms and factors. (shrink)