Background: The way people process trauma and adverse relationships may be more predictive of subsequent adaptation than trauma exposure in itself. However, there is currently no self-report instrument assessing failures in the mentalization of trauma and adverse relationships. Objective: We developed the Failure to Mentalize Trauma Questionnaire (FMTQ) and evaluated its psychometric properties. The FMTQ is a 29-item self-report instrument designed to assess different indications of failures in the mentalization of trauma and adverse relationships. Participants and setting A total of 975 participants (84 % women; 37 % exposed to child maltreatment) were recruited in the course of larger research protocols on parenting. Methods: Participants completed the FMTQ and measures of childhood maltreatment, psychopathology (post-traumatic stress symptoms, dissociative symptoms, level of personality dysfunction), general mentalization and intimate partner violence. Results: Exploratory factor analysis, supported by a confirmatory factor analysis, identified seven factors with good internal consistency that corresponded to different types of failures in the mentalization of trauma and adverse relationships and that loaded on a general factor. A dose-effect association was observed between the severity of childhood maltreatment, and the severity of failures in the mentalization of trauma and adverse relationships (rs = .49, p < .01). The FMTQ total score explained a significant proportion of variance in psychopathology and intimate partner violence, both in participants with histories of childhood maltreatment and participants without childhood maltreatment. Conclusion: The FMTQ is a promising, concise and efficient measure of failures in the mentalization of trauma and adverse relationships that may facilitate clinical screening and research with adults who experienced trauma
