The Department of Justice Appropriations Act, 2015 (Pub. L. 113-235) provides $75 million for the Comprehensive School Safety Initiative (CSSI). This Initiative, originally launched and funded at the same amount in FY 2014, is overseen by the National Institute of Justice (NIJ) within the Office of Justice Programs (OJP), U.S. Department of Justice (DOJ). NIJ carries out this important initiative in collaboration and through consultation with partners from multiple, relevant disciplines, including other executive branch agencies and Congress. In the report accompanying its version of the Commerce, Justice, Science, and Related Agencies appropriations bill (S. 2437), the Senate Committee on Appropriations requested a report on NIJ's progress in developing a strategy and model for comprehensive school safety. CSSI is designed to improve the safety of schools and students nationwide by developing, supporting, and rigorously evaluating school safety programs, practices, and strategies. An important part of the initiative is the partnerships between school professionals and researchers to develop and test approaches that address the real-world safety needs and priorities of America's schools and students. This research-focused, practically-oriented approach is intended to produce knowledge with wide utility and applicability beyond the specific schools that are directly involved in the CSSI. This report describes CSSI, including its goals, guiding principles, activities and accomplishments, and future activities. In FY 2014, NIJ established an interagency working group within the executive branch to provide advice on the initiative, released two solicitations to support pilot projects and research in the field, contributed to national data collection efforts to better understand the nature of school violence, and launched assessments of technologies with the potential to enhance school safety. Funded projects address a wide range of school safety topics, including: (1) School resource officer training and effectiveness; (2) Mental health and trauma-informed response; (3) Exclusionary discipline; (4) Restorative justice; (5) Threat assessment using social media; (6) Positive behavioral interventions and supports; (7) Bullying prevention; (8) Wraparound services/comprehensive approaches; and (9) Protecting students as they walk to and from school.