The Posttraumatic Maladaptive Beliefs Scale (PMBS) was developed to measure maladaptive beliefs about current life circumstances that may occur following trauma exposure. This scale assesses maladaptive beliefs within three domains: (a) Threat of Harm, (b) Self-Worth and Judgment, and (c) Reliability and Trustworthiness of Others. Items for the PMBS were drawn from a larger preexisting measure that assesses a wide range of personal beliefs and reactions associated with trauma exposure. The construct validity of the PMBS was assessed in two independent samples of interpersonal trauma survivors. This article provides data to support the reliability and validity of the PMBS as an instrument to assess general, rather than trauma-specific, maladaptive beliefs that have relevance for functioning in the aftermath of a traumatic event. Moreover, the measure is sensitive to changes that occur in treatment, and the length of the measure (15 items) is practical for use in clinical settings. (Contains 1 table.)