Past research indicates that extralegal factors (e.g., victim age, race, and relationship to assailant) affect police investigative practices in sexual assault cases, including the decision whether to forward a case to prosecutors for further consideration. However, such studies have not distinguished the reasons why cases did or did not move on to prosecutors for criminal charges to be filed. In some instances, law enforcement officials make the decision not to send a case forward for further consideration, but sometimes cases are not referred because victims have withdrawn their participation. Understanding what factors differentiate these outcomes is important for improving the legal response to sexual assault. In this study, 266 police reports of adult sexual assault cases were collected from 3 Midwestern law enforcement agencies (in the same county). Demographic, assault, and evidentiary case characteristics were examined as predictors of case referral outcomes. Results indicated that victims who were unconscious because of alcohol and/or drug use were more likely to withdraw from the investigation process, as were those who did not have a post-assault medical forensic exam. Cases in which law enforcement interviewed a suspect and cases in which police invested moderate to above average investigational effort were significantly more likely to be referred to prosecutors. Abstract published by arrangement with Taylor and Francis.