Mindfulness reduces eating disorder (ED) psychopathology. Self-compassion is a related but distinct construct that may predict other clinical outcomes more strongly than does mindfulness. Previous evidence suggests that self-compassion is associated with less ED psychopathology, although no studies have compared the unique effects of self-compassion and mindfulness. Moreover, few studies have explored mechanisms of this association. The current survey study explored the unique association between self-compassion and ED psychopathology, controlling for mindfulness, as well as whether depressive rumination mediates this association. One hundred and ninety undergraduates completed questionnaires assessing self-compassion, mindfulness, depressive rumination, and ED psychopathology at baseline and five months later. In cross-sectional and longitudinal analyses, self-compassion predicted ED psychopathology even when controlling for mindfulness. By contrast, mindfulness did not predict ED psychopathology when controlling for self-compassion. Depressive rumination mediated the unique association between self-compassion and ED psychopathology in cross-sectional but not longitudinal analyses. The current findings suggest that self-compassion may be a more proximal predictor of ED psychopathology than is mindfulness. Additional research will need to further explore whether depressive rumination is a mechanism of this effect.