The development and validation of a new measure, the Eating Disorder Inventory (EDI) is described. The EDI is a 64 item, self-report, multiscale measure designed for the assessment of psychological and behavioral traits common in anorexia nervosa (AN) and bulimia. The EDI consists of eight sub-scales measuring: 1) Drive for Thinness, 2) Bulimia, 3) Body Dissatisfaction, 4) Ineffectiveness, 5) Perfectionism, 6) Interpersonal Distrust, 7) Interoceptive Awareness and 8) Maturity Fears. Reliability (internal consistency) is established for all subscales and several indices of validity are presented. First, AN patients (N = 113) are differentiated from female comparison (FC) subjects (N = 577) using a cross-validation procedure. Secondly, patient self-report subscale scores agree with clinician ratings of subscale traits. Thirdly, clinically recovered AN patients score similarly to FCs on all subscales. Finally, convergent and discriminate validity are established for subscales. The EDI was also administered to groups of normal weight bulimic women, obese, and normal weight but formerly obese women, as well as a male comparison group. Group differences are reported and the potential utility of the EDI is discussed.