Child sexual abuse (CSA) is a significant issue worldwide, with evidence of its magnitude and impacts on social, emotional, and physical health. Schools have emerged as the center of prevention programs aimed at reducing CSA, with evidence of increased disclosure of CSA victimization by students. The Healthy Relationships Project (HRP), developed by Prevent Child Abuse Vermont, is a primary prevention curriculum implemented across 30 States, including statewide in Vermont. Grounded in the Social Ecological Model, HRP includes training for school staff, six weeks of classroom lessons, and caregiver workshops. A rigorous evaluation study of the HRP is underway in the urban context of high-need and under-resourced DC public and DC public charter schools in Washington, DC, serving Pre-K through 5th-grade students. The evaluation study utilizes a mixed-methods stepped wedge randomized trial design with 15 participating schools, each having, on average, 18 classrooms receiving the HRP intervention. Partnering with DC’s Child Advocacy Center, Safe Shores, primary outcome data includes the number/types of CSA investigations by grade and by school. Improvements in protective behaviors, self-efficacy, knowledge, and disclosure collected from caregivers and staff/faculty at multiple time points inform secondary outcomes. Qualitative research evaluates the strengths and weaknesses of intervention rollout, fidelity monitoring, lessons learned, and sustainability. A presentation from Safe Shores HRP implementation team members and the Northeastern University Research team will share preliminary results and insights, emphasizing best practices, data collection methods, and the challenges of stepped-wedge design in urban, under-resourced environments. Attendees will gain a deeper understanding of the inner workings of the study design along with lessons learned from implementation, data management and engagement strategies. Alongside the presentation, attendees will review and interact with the HRP curricula materials and discuss CSA prevention program challenges and successful tactics for overcoming barriers.