This study analyzes the psychometric properties of the Differentiation of Self Scale-Revised (DSS-R), an instrument assess-ing the differentiation of the self of Spanish adults through the dimensions I Position, Emotional Reactivity, Fusion with Others and Emotional Cutoff, and of a new dimension, Dominance over Others. In Study 1, carried out with 1445 subjects, exploratory factor analysis was performed with one half of the participants, and confirmatory factor analysis with the other, comparing the five-factor and bifactor models. In Study 2, examining convergent validity, 180 subjects participated and completed the revised scale and the Differentiation of Self Inventory-Revised. Studies 3 and 4 verified concurrent validity, with 401 subjects completing the DSS-R and the State-Trait Anxiety Inventory in Study 3, and 170 subjects completing the DSS-R and the Couple Assertion Questionnaire in Study 4. Adequate internal consistency indices and evidence of construct, convergent and concurrent validity were found. The use of the DSS-R is recommended for assessing the differentiation of the self in the Spanish population.
