Sociocultural pressures to be thin and exercise frequency have been reportedly related to female adolescents’ body esteem in previous research. Using 490 female middle school students in Korea, this study examined the mediating role of thin-ideal internalization on the relationships of sociocultural pressure (i.e., parental, peer, and media) and exercise frequency to body esteem. The results indicated that parental pressure only had a direct relationship with body esteem, but no indirect relationship. Media pressure, peer pressure, and exercise frequency were indirectly, but not directly, related to body esteem through thin-ideal internalization. The implications and future directions of research are discussed.