Disturbances in aspects of memory described in current learning and cognitive theories are much more strongly associated with the presence of psychiatric disorder than with mere exposure to traumatic events. In posttraumatic stress disorder (PTSD), there are numerous associated changes that involve memory capacity, the content of memories for trauma, and a variety of memory processes. Whereas some changes appear to reflect the effects of the disorder, other evidence supports a predictive or causal role for memory disturbance. The following aspects of memory are likely to play a causal role in the development or maintenance of PTSD: verbal memory deficits, negative conceptual knowledge concerning the self, overgeneral memory, avoidance or suppression of memories, and negative interpretation of memory symptoms. Other aspects of memory likely to play a causal role that are in addition specific to PTSD are the integration of the trauma with identity, impairment in retrieval of voluntary trauma memories, and increased incidence of sensation-based memories or flashbacks. © 2011 by Annual Reviews. All rights reserved