Acculturation is conceptualized as a multidimensional process but is typically measured as a concurrent movement away from culture of origin as a new cultural orientation is obtained. In this study, the authors examined the overall and subscale scoring systems of the ARSMA-II, the most popular acculturation measure, for its associations with stress, pregnancy anxiety, and birthweight in a large sample of pregnant, Mexican-origin women from the Study for Hispanic Acculturation, Reproduction, and the Environment. As predicted, the ARSMA-II's overall acculturation score and two orthogonal subscales, Mexican orientation and Anglo orientation, revealed differing patterns of associations with stress, pregnancy anxiety, and birthweight. Mexican orientation was negatively associated with stress, positively associated with pregnancy anxiety, and not associated with birthweight. Anglo orientation was positively associated with stress and negatively associated with birthweight. The gains to be made in understanding processes that may change with acculturation by incorporating multidimensional analyses of acculturation are discussed. (Contains 3 tables and 1 note.)