Eating disorders are serious mental health conditions that are accompanied by negative health outcomes, high mortality rates, impaired functioning, and comorbid mental health conditions. Despite many empirically supported interventions for eating disorders, it remains one of the most challenging mental disorders to treat, as individuals often struggle to maintain treatment gains. One method of improving our understanding of effective eating disorder treatment is to identify important processes of change to target during therapy. The aim of the current study was to test two candidate mediators of disordered eating symptom change during residential treatment: self-compassion and body image inflexibility. In the present study, women and adolescent girls (N = 132) completed a battery of measures, including eating disorder severity, self-compassion, and body image inflexibility, at admission to and discharge from a residential eating disorder facility. Our results indicated that changes in body image inflexibility and self-compassion, specifically self-judgment, were both mediators between ED symptom severity from pre- to post-treatment. These results have potential treatment implications, pointing to the possible importance of targeting body image inflexibility, self-judgment, and self-compassion while treating eating disorders.