The impact of traumatic experiences is traditionally examined in the context of posttraumatic stress disorder which assumes a causal link between trauma exposure and psychopathology. The thesis challenges this assumption by implementing a diathesis-stress perspective accounting for stressful event severity and its interaction with two cognitive vulnerability factors modulating posttraumatic outcome: self-control and appraisal. Self-control variables of impulsive behavioral tendencies and emotion regulation differentially impacted outcome as a function of trauma, such that adaptive and maladaptive emotional responses were observed. Negative appraisals of the self were related to posttraumatic symptoms regardless of stressful event severity, while memory appraisals for mainly positive events were less intense as a function of stressful event severity. In line with the diathesis-stress perspective, the overall findings demonstrated that stressful event severity is a catalyst for activating vulnerability factors associated with posttraumatic symptoms, and that posttraumatic outcome is a dimensional representation encompassing psychopathology and resilience.