Shattered assumptions theory posits that each individual has a core set of assumptions about the world and the self, often termed the assumptive world which includes: the world is a benevolent place, the world is meaningful, and the self is worthy. Experiencing a traumatic event is believed to lead individuals to question these assumptions in light of the new contradictory information that causes the assumptive world to shatter, leaving the individual to rebuild a more negative perception of the world and themselves. This rebuilding of a fragile new set of core beliefs is believed to be a cause of posttraumatic stress disorder (PTSD) symptoms. Although shattered assumptions theory has been widely accepted in the field of trauma psychology, the shattering of the assumptive world has not been empirically supported due to measurement issues and poor research designs. The current study implemented a prospective design to assess a new measure of the individual’s assumptive world when there is an intervening trauma. In a college sample (N = 336), individuals who experienced a traumatic event over the course of the semester (n = 40) evidenced decreases in optimism in their assumptive worlds, in comparison to individuals who did not experience a traumatic event. The results suggest there is a limited shattering of the assumptive world for those who experienced a traumatic event. Applications, limitations and future directions are discussed.