Longitudinal associations between eating disorders (EDs) and comorbid psychiatric disorders are poorly understood but important to examine as comorbidities are common and can impede ED recovery. We examined two common comorbidities, major depressive disorder (MDD) and substance use disorder (SUD), in adult women with intake diagnoses of anorexia nervosa (AN) and bulimia nervosa (BN) who participated in a longitudinal study. To test the longitudinal reciprocal relations among ED, MDD, and SUD, we conducted a multi-group autoregressive cross-lagged path analysis. We tested whether ED, MDD, and SUD in a given three-month period (t – 1) each predicted ED, MDD, and SUD during the subsequent three-month period (t) over 5years. We examined the moderating effect of intake diagnosis (AN vs. BN). Among AN (but not BN) participants, having MDD at t – 1 predicted having an ED at time t, OR=1.98, B=.68, z=2.49, p=.01. Among BN (but not AN) participants, having a SUD at t – 1 predicted having an ED at time t, OR=5.16, B=1.64, z=2.34, p=.01. In contrast, having an ED at t – 1 did not predict MDD or SUD at time t for AN or BN participants. These results suggest for individuals with AN and MDD, treating MDD may facilitate ED recovery. For individuals with BN and SUD, treating SUD may facilitate ED recovery. These identified temporal associations between ED and comorbid disorders may guide cognitive behavioral researchers and therapists in prioritizing treatment targets given the high rate of comorbidity in EDs.