The aim of this study was to test hypotheses derived from a model that explains both the comorbidity of problem drinking and eating disorder symptoms and the difference in risk process between the two disorders. In Study One, the authors examined four personality constructs typically associated with rash action (sensation seeking, lack of planning, lack of persistence, and negative urgency) and disorder-specific expectancies in samples of women with eating disorders, substance dependence disorders, comorbid conditions, and no symptoms (N = 104). Negative urgency, the tendency to act rashly when distressed, differentiated the disordered groups from the control group. In contrast, learned expectancies differentiated among clinical groups. Women with eating disorders endorsed high levels of eating and dieting expectancies and women with substance use disorders endorsed high levels of alcohol expectancies, while comorbid women endorsed high levels of both. In Study Two, this pattern of findings was replicated in a sample of fifth grade girls (N = 905). Girls who had engaged in binge eating, alcohol use, or both had higher levels of negative urgency than asymptomatic girls, and the pattern of outcome expectancy endorsement was disorder specific. Negative urgency may represent a general, personality influence on both eating disordered behaviors and symptoms of alcohol dependence, which, when combined with learned, behavior-specific expectancies, leads to specific addictive behavior patterns.