Identity theorists have emphasized the importance of integration across identity domains for psychosocial well-being. There remains little research, however, on associations across identity domains, group differences across identity profiles, and the joint association of multiple identity domains with academic outcomes. This dissertation includes two studies that address these limitations in the identity literature. Study 1, examined the ego-social identity profiles that emerged from ethnic identity exploration and commitment, American identity exploration and commitment, and ego identity integration and confusion among an ethnically diverse sample of emerging adults using latent profile analysis (N = 8,717). Results suggested that an eight-profile solution was the best fit for the data. The profiles demonstrated differences in identity status and salience across identity domains. Significant ethnic, sex, nativity, and age differences were identified in ego-social identity membership. Study 2 focused on the ego-social identity profiles that emerged from the same identity domains among biethnic college students of Latino and European American heritage (N = 401) and how these profiles differed as a function of preferred ethnic label. The association of ego-social identity profile with academic achievement and the moderation by university ethnic composition were examined. Results indicated that a two-profile solution was the best fit to the data in which one profile included participants with general identity achievement across identity domains and one profile included individuals who were approaching the identity formation process in each domain. Ego-social identity profile membership did not differ based on preferred ethnic label. Individuals who had a more integrated identity across domains had higher college grades. University ethnic composition did not significantly moderate this association. Taken together, these two studies highlight the intricacies of identity formation that are overlooked when integration across identity domains is not considered.