Anxiety disorders are the most prevalent psychological disorders during emerging adulthood. Some consistent gender differences have been reported in anxiety with women suffering more anxiety than men, which has detrimental consequences in most life spheres in the youth and later life stages. The understanding of the development of anxiety in emerging adulthood requires a developmental perspective. The Developmental Assets Theory was postulated to describe the individual and the contextual resources which may foster positive youth development and mental health. The present study aims to analyze to what extent the gender differences in anxiety may be partly explained by gender differences in developmental assets. For this purpose, a cross-sectional study was conducted in which a sample of 1,044 youths (75.5% women; age range = 18–28; M age = 20.47, SD = 3.08) enrolled in 11 universities from different regions in Spain filled in self-report measures of developmental assets and anxiety symptoms. The participants completed an online survey with the scales, Developmental Assets Profile developed by the Search Institute (1) and Generalized Anxiety Disorder-7 (GAD-7) (2). The results showed more anxiety in the female subsample (at both the symptoms and clinical levels). Some gender differences in developmental assets were also observed. A partial mediation model, based on regression analyses, indicated that gender differences in anxiety were partly explained by gender differences in developmental assets. Thus, higher anxiety in the women was partly due to lower scores in positive identity and higher scores in positive values. These results suggested the need to design programs to prevent anxiety with specific measures for women youth to nurture positive identity and promote strengths and coping skills that allow them to get the benefits of well-being derived from positive values, thus, preventing worry and stress overload, which may lead to anxiety.