Many studies in the sexual assault literature have found a significant relationship between sexual assault severity and psychological distress, specifically PTSD and suicidality. However, in the current literature, there is an inconsistent and incomplete definition of the construct of assault severity. The present study aims to create a comprehensive self-report questionnaire, called the Sexual Assault Severity Scale (SASS) that includes assault characteristics, such as victim-offender relationship, substance use, and peritraumatic responses, and cognitive variables, such as posttraumatic schema disruptions and coping self-efficacy in the conceptualization of assault severity. Two models evaluating the relationship between assault severity and post assault distress were compared, one using the SASS to measure assault severity and the other using the Sexual Experiences Scale-Long Form Victimization (SES-LFV; Koss et al., 2007). The results of the psychometric analysis suggest that the SASS is a reliable and valid measure of assault severity. This study also found evidence supporting the use of a direct assessment of perceived severity, rather than a hierarchical ranking of victimization severity, when measuring the construct of sexual assault severity. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]