This study aimed to prospectively examine the role of peer and media influences in the development of body satisfaction (incorporating the desire for thinness and satisfaction with appearance) in young girls, as well as the relationship between body satisfaction and self-esteem. A sample of 97 girls 5-8 years of age completed individual interviews at Time 1 and 1 year later at Time 2. Linear panel analyses found that Time 1 perception of peers' desire for thinness was temporally antecedent to girls' desire for thinness, appearance satisfaction, and self-esteem 1 year later. In addition, the watching of appearance-focused television programs was temporally antecedent to appearance satisfaction. Finally, girls' desire for thinness was found to temporally precede low self-esteem. Thus, as early as school entry, girls appear to already live in a culture in which peers and the media transmit the thin ideal in a way that negatively influences the development of body image and self-esteem.