This is the second and final report summarizing findings from an impact evaluation of a violence prevention intervention for middle schools. This report provides findings from the second and third years of the 3-year intervention. The U.S. Department of Education (ED) contracted with RTI International and its subcontractors, Pacific Institute for Research and Evaluation (PIRE) and Tanglewood Research, Inc., to conduct an evaluation of a hybrid intervention model that combines a curriculum-based program, Responding in Peaceful and Positive Ways (RiPP [Meyer and Northup 2002a, 2002b, 2006]), and a whole-school approach, Best Behavior (Sprague and Golly 2005). The combined intervention was administered over the course of 3 successive years. Using a randomized control trial design (with entire schools randomly assigned either to receive the intervention or not), the evaluation assessed the intervention's effects on both the full sample of students as well as on students at high risk for committing violence. Tanglewood Research provided implementation oversight along with site-based liaisons and coordinated training and technical assistance for staff in intervention schools. The developers of the two programs that constitute the intervention—Prevention Opportunities and University of Oregon—provided the program materials and conducted staff training. An earlier report presented findings after 1 year of program implementation (Silvia et al. 2010).