A substantial majority of individuals who are exposed to a traumatic event do not develop any persistent trauma-related psychological symptoms, a phenomenon referred to as resilience. Relying on a sample of undergraduate students (n = 79), the present study investigated whether positive and negative affect and cognitive reactivity to emotional challenges serve as predictors of longitudinal changes in resilience as measured by the connor-davidson resilience scale. While at initial testing both positive affect and cognitive reactivity were related to resilience, only higher levels of cognitive reactivity predicted a reduction in resilience four months later. These results highlight the relevance of cognitive reactivity for the study of resilience. (netherlands journal of psychology, 65, 62-68.).