The unidimensional model of acculturation posits that heritage and mainstream culture identifications have a strong inverse relation, whereas the bidimensional model posits that the 2 identifications are independent. The authors compared these models in 3 samples of ethnic Chinese (ns = 164, 150, and 204), 1 sample of non-Chinese East Asians (n = 70), and one diverse group of accultumting individuals (n = 140). Although the unidimensional measure showed a coherent pattern of external correlates, the bidimensional measure revealed independent dimensions corresponding to heritage and mainstream culture identification. These dimensions displayed patterns of noninverse correlations with personality, self-identity, and psychosocial adjustment. The authors conclude that the bidimensional model is a more valid and useful operationalization of acculturation. The culture in which people live plays an important role in shaping their sense of self. Indeed, one facet of people's selfidentity is that they belong to a certain cultural group. Thus, they have a sense of themselves as being, for example, Canadian, American, or Chinese. When an individual moves from one culture to another, many aspects of self-identity are modified to accommodate information about and experiences within the new culture. This process, generally referred to as acculturation, involves changes that take place as a result of continuous and direct contact between individuals having different cultural origins (Redfield, Linton, & Herskovits, 1936). Such changes may be observed in a number of different domains, including attitudes, behaviors, values, and sense of cultural identity. At a fundamental level, then, acculturation involves alterations in the individual's sense of self. An examination of the extant literature on the acculturation process reveals two predominant formulations, which we term the Studies 1 and 2 were part of a master's thesis conducted by Andrew G. Ryder under the supervision of Lynn E. Alden. Preparation of this article was facilitated by research grants from the Social Sciences and Humanities Research Council of Canada. We thank Luke Conway, Jennifer Ritsher, Bryan Sokol, Roger Tweed, and Michelle Yik for their helpful comments on earlier versions of this article; John Berry and Richard Suinn for providing unpublished instruments that aided in the development of the