Eating disorder symptomatology is highly prevalent in adolescence and is regarded one of the most important precursors of clinical eating disorders. The present longitudinal study examined the development of eating disorder symptomatology in adolescents over two years. At Time 1,528 high school students filled out self-report questionnaires (50.5% female; Mage = 15 years). Multivariate latent growth curve modeling and latent class growth analyses were performed to model latent trajectories and to identify latent trajectory classes. Stable trajectories of drive for thinness and body dissatisfaction were found, whereas bulimia and BMI increased over time. Important gender differences pointed to girls experiencing more eating disorder symptoms at each time point. Additionally, more diverse trajectory classes were found in girls than in boys. Finally, classes with the most eating disorder symptoms also experienced the most problems in identity development, internalizing symptoms, and the least effortful control. The present study underscores the importance of identifying vulnerable adolescents that experience greater eating disorder symptomatology, as they also seem to experience the worst psychosocial development.