Objective: We conducted a randomized, controlled preliminary trial to examine the effect of a dissonance-based eating disorder program on eating disorder symptoms and cardiac risk indices in a community sample of women with subclinical and clinical symptoms (N = 47), examining the efficacy of the program in both the indicated prevention and treatment realms. Method: Eating disorder symptoms, body mass index, and biomarkers of cardiac risk were examined in dissonance and assessment-only control conditions at baseline, postintervention, and 2-month follow-up. Specifically, we assessed mean R wave amplitude, QT interval length, vagal tone (high frequency spectral power of heart rate variability), and sympathetic tone (low/high frequency spectral power ratio) via electocardiography (ECG) at each assessment period. Results: We predicted a statistically significant 2 (condition: control, dissonance) x 3 (time: baseline, postintervention, 2-month follow-up) interaction in the mixed factorial MANOVA results. Results confirmed this hypothesis. Eating disorder symptoms and cardiac risk indices decreased significantly among participants in the dissonance condition at postintervention and 2-month follow-up compared with baseline. Conclusion: Results provide support for the efficacy of a dissonance-based program in the reduction of eating disorder symptoms and cardiac risk indices among women with subclinical and clinical eating disorder symptoms. Findings establish the efficaciousness of this dissonance-based approach in the indicated prevention and treatment realms and establish its efficacy in reducing cardiac risk indicators.