The current study examined emerging adults' gender identity and its link with several gender-related and social outcomes, by using a novel dual-identity approach that was originally developed in children. Dutch emerging adults between 18 and 25 years old (N = 318, M[subscript age] = 21.73, SD = 2.02; 51% female) indicated their similarity to the own-gender group and the other-gender group to assess gender identity. They completed questionnaires assessing gender-typed behavior (internalized sexualization, toughness, emotional stoicism) and attitudes (i.e., sexism); friendship efficacy and ability; and social-emotional adjustment. Cluster analysis on the gender-identity items revealed four gender-identity types: (a) feeling similar to one's own gender, but not to the other gender (Own-GS); (b) feeling similar to both one's own and the other gender (Both-GS); (c) feeling dissimilar to one's own gender (Low-Own-GS); and (d) feeling similar to neither gender (Low-GS). Own-GS and Low-GS adults were most gender-typed in their behavior and showed sexist attitudes. Both-GS adults felt efficacious and were highly able to relate to both genders, whereas the other groups felt efficacious and were able to relate to only one gender (Own-GS, Low-Own-GS), or to neither gender (Low-GS). Low-Own-GS and Low-GS were least well-adjusted social-emotionally. Findings suggest that identifying with one's own gender is helpful for certain aspects of social-emotional adjustment but that also identifying with the other gender provides the advantage of flexible social and interpersonal skills and egalitarian gender attitudes.