ABSTRACT This study examined the prospective association between self-concept clarity and sociocultural appearance processes (internalization of the thin-body ideal and appearance-based social comparisons). Adolescent girls (n = 153; mean age = 15.76 years) completed measures at two separate timepoints, three months apart. Path analysis showed that lower self-concept clarity prospectively predicted higher thin-ideal internalization and appearance comparisons. In contrast, the reverse model showed that thin-ideal internalization and appearance comparisons did not prospectively predict self-concept clarity. Finally, including self-esteem in the model showed that self-concept clarity, but not self-esteem, prospectively predicted thin-ideal internalization and appearance comparisons. These findings suggest that low self-concept clarity may increase vulnerability to sociocultural appearance processes that increase the risk for body dissatisfaction.