The aim of this study is to identify psychological processes related with posttraumatic stress symptoms (PTS) and posttraumatic growth (PTG). Through a path analysis it was evaluated a model that related the PTS and PTG with subjective severity of trauma, impact on the basic beliefs, social sharing and rumination related to an event. Were selected 291 college students who were exposed to the earthquake and tsunami in Chile, 2010. The final model obtained shows that the PTS and PTG are produced by different routes, even when in some phases the same psychological variables are involved such as the subjective severity and social sharing. The intrusive rumination appears as a mediator of the PTS and the deliberate rumination of the PTG.