The Difficulties in Emotion Regulation Scale (DERS) is extensively used as a measure of emotion (dys-)regulation ability in both clinical and nonclinical populations. This is the first study to examine the factor structure of both the original 36-item and short 16-item version of the DERS in adults with eating disorders and to test measurement invariance across diagnostic subgroups. The factor structure of the scale was examined using confirmatory factor analysis in a psychiatric sample of adults with eating disorders (N = 857). Four primary factor structures were fitted to the data: (1) a unidimensional model, (2) a six-factor correlated-traits model, (3) a higher-order factor solution, and (4) a bifactor model. Measurement invariance was tested for diagnostic subgroups of anorexia nervosa and bulimia nervosa and associations between factors and eating pathology were examined in each diagnostic group. Results indicated that a modified bifactor solution fitted the data adequately for both the 36-item and 16-item version of the DERS. A general factor explained most of the variance (86%) and reliability was high for the general factor of DERS (total) but lower for the subscales. Measurement invariance of the bifactor model was supported across diagnostic subgroups and test of factor means reveled that bulimia nervosa had a higher factor mean than anorexia nervosa on the general factor. The general factor accounted for a significant proportion of variance in eating pathology. Our results support the use of the total scale of both the 36-item and 16-item version among adults with eating disorders.