Since the tragedy at Columbine High School in 1999, one of the worst school mass shootings in U.S. history, school administrators and researchers in Colorado and elsewhere have been searching for solutions to identify and mitigate the impact of bullying and school climate on threats to school safety. Fortunately, numerous studies over the past two decades have focused on developing and evaluating evidence-based prevention programs to improve the safety and well-being of American youth at school. National Institute of Justice-supported researchers studied the outcomes of two cohorts (10 schools and 36 schools, respectively) after years one and two using a randomized controlled trial with staggered Safe Communities Safe Schools (SCSS) model implementation. Results from the study indicated that schools did have sufficient initial readiness to implement the SCSS model. However, the model yielded limited impacts on school climate, safety, behavioral and mental health indicators, and academic outcomes, with outcomes varying by degree of fidelity to model implementation.