Background--Outcomes in peripartum cardiomyopathy (PPCM) vary. We sought to determine whether severity of left or right ventricular dysfunction (RVD) at PPCM diagnosis differentially associates with adverse outcomes. Methods and Results--We conducted a single-center retrospective cohort study of 53 patients with PPCM. The primary outcome was a composite of left ventricular assist device implantation, cardiac transplantation, or death. We used Kaplan-Meier curves to examine event-free survival and Cox proportional hazards models to examine associations of left ventricular (LV) ejection fraction <30%, LV end-diastolic diameter ≥60 mm, and moderate-to-severe RVD at PPCM diagnosis with the primary outcome. Median (interquartile range) follow-up time was 3.6 (1.4-7.3) years. Seventeen patients (32%) experienced the primary outcome, of whom 11 had moderate-to-severe RVD at time of PPCM diagnosis. Overall event-free survival differed by initial RVD severity and LV ejection fraction <30%, but not by LV end-diastolic diameter ≥60 mm. In univariable analyses, LV ejection fraction <30% and moderate-to-severe RVD were associated with the outcome (hazard ratios [95% confidence intervals] of 4.85 [1.11-21.3] and 4.26 [1.47-11.6], respectively). In a multivariable model with LV ejection fraction <30%, LV end-diastolic diameter ≥60 mm, and moderate-to-severe RVD, only moderate-to-severe RVD was independently associated with the outcome (hazard ratio [95% confidence interval], 3.21 [1.13-9.10]). Although most outcomes occurred within the first year, nearly a third occurred years after PPCM diagnosis. Conclusions--Initial moderate-to-severe RVD is associated with a more advanced cardiomyopathy phenotype and increased risk of adverse outcomes in PPCM, within and beyond the first year of diagnosis. By identifying a worse PPCM phenotype, initial moderateto- severe RVD may prompt earlier consideration of advanced heart replacement therapies.