Sexual assault of women is common on college campuses, but the vast majority of victims do not make a formal report. It is imperative to understand these decisions to help design and implement policies to normalize and encourage reporting. This study aimed to extend science on the thematic reasons for non-reporting by (1) establishing validity for rational and empirical models of overarching themes, and (2) examining differences in the most common thematic reasons for non-reporting. A five-theme rational model of reasons for non-reporting campus sexual violence (CSV) was developed based on the literature, with 25 specific reasons under these themes. Part 1 of the study consisted of 25 experts in the field of campus sexual violence who rated the relevance to non-reporting of the five themes and specific reasons using a 4-point Likert scale. Based on the Content Validity Index (CVI), all five themes of the rational model were retained, as well as 18 specific items that fall under these themes, suggesting experts saw these as relevant to non-reporting. Part 2 involved a national sample of 431 female college student victims who did not report their sexual assault to law enforcement or university personnel. Participants selected which of the original 25 reasons for non-reporting applied to them for different types of CSV. Exploratory factor analyses produced empirical models which varied in terms of number of thematic factors and item groupings. In Part 3, the frequency of the endorsement of the themes from each model in Part 1 and 2 were examined using the sample of 431 undergraduates. Results showed across models, common themes included those related to personal reasons (i.e., rational model) and emotions and beliefs about reporting (i.e., empirical models). Gathering a clearer understanding of overarching themes of non-reporting is pivotal to targeted policy reform, university prevention systems, and clinical treatment, with the goal of providing a safer campus for students. [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.]