Abstract: Given mixed findings regarding the unique trajectories of female and male adolescents' body dissatisfaction over time, comprehensive longitudinal examinations are needed. This 10-year longitudinal, population-based study, with 1902 participants from diverse ethnic/racial and socioeconomic backgrounds in the Minneapolis/St. Paul metropolitan area, examined changes in body dissatisfaction from adolescence to young adulthood. Results revealed that: (a) female and male participants' body dissatisfaction increased between middle and high school, (b) body dissatisfaction increased further during the transition to young adulthood, and (c) this increase was associated with an increase in BMI over time, such that the upward trend in body dissatisfaction became nonsignificant when BMI was controlled. These results highlight a trend in which diverse female and male youth are increasingly dissatisfied with their bodies as their BMI increases from middle school to young adulthood, and emphasize the need for targeted prevention efforts to intervene in this trajectory and mitigate potential harm.