Weight and body image concerns are prevalent among adolescents across cultures and pose significant threats to well-being, yet there is a paucity of longitudinal research on samples living in non-Western and developing countries. This prospective study assessed the extent to which select sociocultural, psychological, and biological risk factors contributed to changes in weight esteem among adolescent girls and boys living in the People's Republic of China. Students (181 boys, 320 girls) from middle schools and high schools in Southwest China completed measures of demographics; weight esteem; thin female and lean, muscular male appearance ideals; positive and negative affect; and appearance-based social pressure, teasing, and comparison. Subsequently, weight esteem was reassessed 18 months later. Girls having stronger preferences for thin ideals, a high body mass index, and more negative affect at Time 1 were more likely to experience losses of weight esteem at follow-up. Among boys, high baseline levels of appearance pressure contributed to later reductions in weight esteem--an effect that was also moderated by age. For both sexes, appearance social comparisons also contributed to weight esteem changes in univariate analyses, albeit these effects were attenuated within multivariate prediction models. In sum, this study highlights how specific experiences implicated previously in research on body dissatisfaction in Western samples are also salient in understanding changes in weight esteem for adolescent girls and boys in rapidly developing China. (Contains 5 tables.)