Depersonalization is a type of dissociation characterized by feelings of unreality and detachment from one's sense of self. Despite a history rich in clinical description, the construct of depersonalization has proven difficult to define and measure. Available measures vary substantially in content, and all have relatively limited psychometric support. In this study the content validity, internal consistency, and convergent and discriminant validity of 3 depersonalization measures were compared in a sample of 209 trauma-exposed college students. Measures were the Dissociative Experiences Scale ( E. M. Bernstein & F. W. Putnam, 1986 ), Cambridge Depersonalization Scale (CDS; M. Sierra & G. E. Berrios, 2000 ), and Multiscale Dissociation Inventory (MDI; J. Briere, 2002 ). All 3 measures exhibited adequate to high internal consistency for the depersonalization-derealization items. Based on D. Westen and R. Rosenthal's (2003) procedure for quantifying construct validity, the CDS and MDI demonstrated the best fit with the predicted pattern of correlations with measures of other constructs. The CDS and MDI also demonstrated the strongest evidence of content validity. Overall, the results most strongly support the use of the CDS and MDI for assessing depersonalization in this population.