Psychiatric comorbidities are prevalent in youth eating disorders. In a sample of 1,906 youth from the United States (49.2% female), followed from elementary school into high school, we found support for a model to help explain this comorbidity. Endorsement of binge eating in fifth grade (elementary school) predicted increases in negative urgency, negative affect, and lack of planning in seventh grade (middle school). In turn, seventh grade negative urgency predicted increases in 10th grade (high school) externalizing dysfunction (binge eating, alcohol use problems, and smoking) and internalizing dysfunction (depressive symptoms). Seventh grade negative affect predicted increases in 10th grade binge eating and depressive symptoms. Seventh grade lack of planning predicted increases only in 10th grade externalizing behaviours. Early engagement in binge eating may elevate risk for multiple forms of dysfunction, at least in part due to its prediction of high-risk personality change in middle school.