683,000 women are sexually assaulted annually in the United States, half of whom develop chronic posttraumatic stress disorder (PTSD) and thus have markedly increased risk for cannabis use disorder (CUD). The current proposal will test the acceptability, initial efficacy, and mechanisms underlying a novel digital therapeutic targeting risk for PTSD-CUD, which could address the critical need for PTSD-CUD prevention for the 100,000 women who annually present for emergency care after sexual assault. In this research context, the applicant will receive key training in multisite, emergency-care based randomized clinical trials (RCTs), advanced statistical analyses for RCTs and ecological momentary assessment data, biobehavioral mechanisms underlying PTSD-CUD prevention, and professional development, launching her independent research career focused on reducing the public health burden of PTSD-CUD among sexual assault survivors by leveraging digital therapeutics.