This study used a feminist psychodynamic developmental framework to test the hypothesis that internalizing conventional femininity ideologies in two domains--inauthenticity in relationships and body objectification--is associated with early adolescent girls' mental health. One hundred forty-eight eighth-grade girls completed measures of femininity ideology, self-esteem, depression, and demographic characteristics. In the first part of this study, we refined the Adolescent Femininity Ideology Scale originally developed by Tolman and Porche (2000). In the second part, we used structural equation modeling to test models linking femininity ideology to mental health. Results revealed that body objectification, and to a lesser extent, inauthenticity in relationships, accounted for half of the variance in depression and over two-thirds of the variance in self-esteem in a critical period of development for adolescent girls. The importance of a feminist psychodynamic developmental framework for identifying and understanding salient dimensions of female adolescence is discussed.