Most sexual assaults are never reported to law enforcement, and even among reported cases, most will never be successfully prosecuted. This reality has been a long-standing source of frustration for survivors, victim advocates, as well as members of the criminal justice system. To address this problem, communities throughout the United States have implemented multidisciplinary response interventions to improve post-assault care for victims and increase reporting and prosecution rates. One such model is the Sexual Assault Nurse Examiner (SANE) program, whereby specially trained nurses (rather than hospital emergency department [ED] physicians) provide comprehensive psychological, medical, and forensic services for sexual assault victims. The purpose of this study was to examine whether adult sexual assault cases were more likely to be investigated and prosecuted after the implementation of a SANE program within a large Midwestern county. A quasi-experimental design was used to compare criminal justice system case progression pre-SANE to post-SANE. Results from longitudinal multilevel ordinal regression modeling revealed that case progression through the criminal justice system significantly increased pre- to post-SANE: more cases reached the "final" stages of prosecution (i.e., conviction at trial and/or guilty plea bargains) post-SANE. These findings are robust after accounting for changes in operation at the focal county prosecutors' office and seasonal variation in rape reporting. Implications for policy and practice are discussed.