Abstract: Adolescents’ appearance-related concerns can provoke increasing emotional, social, and eating-related problems. The aims of this five-wave (2.5-year), multiple-informant longitudinal study were to (a) examine growth trajectories of appearance anxiety symptoms and appearance esteem, (b) identify whether trajectories differed by gender, and (c) examine several launching factors including parent-reported physical maturation, peer-rated physical appearance, body mass index, and appearance teasing by parents and peers. Participants were 387 adolescents (44% boys) aged 10 to 13 years at the first assessment. Steep growth in appearance anxiety symptoms was found for both girls and boys, but there was no average change in appearance esteem. Girls had more elevated appearance anxiety symptoms and lower appearance esteem than boys, girls’ body mass index was associated with symptoms, and earlier physical maturation and teasing about appearance, alone and in combination, were associated with growth in appearance anxiety symptoms for girls and boys. Earlier maturing boys who were highly teased by parents, but even more so when teased by peers, were at utmost risk for elevated appearance anxiety symptoms and increasing symptoms over time. In contrast, all girls exhibited elevated or increasing appearance anxiety symptoms across time, with the exception of girls with the latest maturation who also reported little teasing about their appearance.