This study examined the construct validity and clinical utility of S. Nolen-Hoeksema's (1991) Response Styles Questionnaire (RSQ) Rumination scale. Eighty-eight participants with recent-onset major depressive episodes were assessed and followed for 6 months, using semistructured interviews and self-report inventories. The RSQ Rumination scale exhibited poor 6-month stability and appeared to be closely linked to participants' clinical status-mood state. The scale was significantly correlated with conceptually related constructs such as emotion-focused coping, negative affectivity-temperament, and self-criticism. However, baseline negative temperament and self-criticism predicted key aspects of the 6-month course and outcome of major depressive episodes, whereas baseline rumination did not. Finally, rumination appeared to be closely associated with the severity of the depressive episode, rather than defining a distinct clinical subtype.