The authors addressed 5 issues bearing on the validity of the construct of depressive personality disorder (DPD): its relationship with the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; American Psychiatric Association, 1987) mood and personality disorders and normal personality dimensions of negative and positive affectivity, its stability over 30-months, and its impact on the course of Axis I depressive disorders. Two samples were used: 156 outpatients with mood disorders, personality disorders, or both, and 267 of their 1st-degree relatives. The association between DPD and dysthymia was fairly modest, whereas the associations with major depression and the personality disorders were quite low. DPD was moderately correlated with both negative and positive affectivity; however, it contributed unique information beyond that available from the 2 emotional superfactors. Finally, DPD was moderately stable over a 30-month period and was associated with a poorer course of depression.