Teasdale's (Teasdale, J.D. (1988). Cognitive vulnerability to persistent depression. Cognition and Emotion, 2, 247-274) differential activation hypothesis refers to the ease with which maladaptive cognitive processes are triggered by mild dysphoria as cognitive reactivity. Supporting this model is evidence of a differential association between sad mood and dysfunctional cognitions in formerly depressed and never-depressed individuals and the finding that cognitive reactivity predicts depression recurrence in remitted depressives. The Leiden Index of Depression Sensitivity-Revised (LEIDS-R; Van der Does, A.J.W., Williams, J.M.G. (2003). Leiden Index of Depression Sensitivity-Revised (LEIDS-R). Retrieved September 4, 2007, from http://www.dousa.nl/publications_depression.htm#LEIDS) is a recently developed self-report measure that provides clinicians and researchers with a time-efficient means by which to assess cognitive reactivity. This study investigated the relationship between cognitive reactivity (indexed by the LEIDS-R) and depressive rumination in a nonclinical sample (N = 324). As predicted, partial correlations between the LEIDS-R (subscale and Total scores) and the Ruminative Response Scale (RRS; Nolen-Hoeksema, S., and Morrow, J. (1991). A prospective study of depression and posttraumatic stress symptoms after a natural disaster: The 1989 Loma Prieta earthquake. Journal of Personality and Social Psychology, 61, 115-121) were significant after controlling for current depressive symptoms. A subsample of participants (n= 130) was administered a structured interview to determine current and past depression diagnostic status. Recovered depressed individuals scored more highly on the LEIDS-R Total and LEIDS-R Rumination subscale; however, the groups did not differ on the remaining subscales. Regression analyses indicated that (across all participants) LEIDS-R Total made a unique contribution to the prediction of depression over and above trait level of depressive rumination. Overall, the LEIDS-R is a time-efficient self-report index of cognitive reactivity that demonstrates promise in distinguishing recovered and never-depressed individuals.