The notion that traumatic events shatter survivors' fundamental assumptions about the world has been accepted as a truism in the trauma literature, although tests of this hypothesis provide a somewhat mixed picture. Because this research has relied heavily on the World Assumptions Scale (WAS), it is unclear whether these inconsistent results are due to problems with assumptive world theory, improper tests of the theory, or problems with the WAS. Data were gathered from 742 undergraduate students at four universities to assess the psychometric properties of the WAS. Findings suggest several shortcomings of the WAS, including temporal instability, and mixed evidence regarding construct validity. Implications for trauma research are discussed.