The prevalence of social anxiety during adolescence is high, and it is necessary that we increase our knowledge on the related factors that contribute to social anxiety. The present study sought to examine the relationships among self-esteem, body-esteem, and social anxiety among adolescent students, as well as to examine the mediating role of body-esteem between self-esteem and social anxiety, and to examine the moderating roles of weight and gender between body-esteem and self-esteem with social anxiety. The participants comprised 520 high-school students from eight high schools in Tehran city in District 11 of the Ministry of Education in 2012/13. Structural equation modelling showed that adolescents with poor self-esteem and poor body-esteem were more likely to show social anxiety. Body-esteem partially mediated between self-esteem and social anxiety. Weight and gender moderated between body-esteem and self-esteem with social anxiety. Our results highlight the roles of body-esteem and self-esteem as promising avenues for reducing social anxiety among adolescent students.