Wegner's seminal investigations of effects of thought suppression on later thought frequency have had a significant impact on recent approaches to understanding emotional disorders characterized by the occurrence of persistent, repetitive, unwanted thoughts. Thought suppression has now been implicated as a etiological and/or maintaining factor in depression, generalized anxiety disorder, specific phobia, posttraumatic stress disorder and obsessive-compulsive disorder. These developments are fairly new, and it has not been until recently that studies have investigated the effects of suppressing thoughts that are actually analogous to problematic thoughts characteristic of emotional disorder. This paper provides a review of this body of work, including the findings and their relevance for existing models of specific disorders. Directions for future research are suggested. (C) 1999 Elsevier Science Ltd. All rights reserved.