Aims: To summarize literature data about the role of psychosocial factors in the etiology of bruxism. Methods: A systematic search in the National Library of Medicine's PubMed Database was performed to identify all peer-reviewed papers in the English literature dealing with the bruxism-psychosocial factors relationship. All studies assessing the psychosocial traits of bruxers (by using questionnaires, interviews, and instrumental and laboratory exams) and reviews discussing the contribution of those factors to the etiology of bruxism were included in this review. Results: A total of 45 relevant papers (including eight reviews) were retrieved with a search strategy combining the term "bruxism" with the words stress, anxiety, depression, psychosocial and psychological factors. The majority of data about the association between psychosocial disorders and bruxism came from studies adopting a clinical and/or self-report diagnosis of bruxism. These studies showed some association of bruxism with anxiety, stress sensitivity, depression and other personological characteristics, apparently in contrast with sleep laboratory investigations. A plausible hypothesis is that clinical studies are more suitable to detect awake bruxism (clenching type), while polysomnographic studies focused only on sleep bruxism (grinding type). Conclusion: Wake clenching seems to be associated with psychosocial factors and a number of psychopathological symptoms, while there is no evidence to relate sleep bruxism with psychosocial disorders. Future research should be directed toward the achievement of a better distinction between the two forms of bruxism in order to facilitate the design of experimental studies on this topic. Keywords: anxiety, bruxism, depression, etiology, psychosocial factors, stress