There is a growing call to identify specific outcome predictors in real-world eating disorder (ED) treatment settings. Studies have implicated several ED treatment outcome predictors [rapid response (RR), weight suppression, illness duration, ED diagnosis, and psychiatric comorbidity] in inpatient settings or randomized controlled trials of individual outpatient therapy. However, research has not yet examined outcome predictors in intensive outpatient programs (IOP). The current study aimed to replicate findings from randomized controlled research trials and inpatient samples, identifying treatment outcome predictors in a transdiagnostic ED IOP sample.