While widely considered a core pillar of the peace and security architecture, Security Sector Reform (SSR) is coming under fire. SSR theory and practice are criticized for being overly focused on traditional conflict and post-conflict settings and for being unable to adjust to unconventional settings marked by chronic crime and terrorism. SSR tends to be disproportionately focused on national institutions and less amenable to engaging at the subnational scale. Drawing on the experiences of so-called 'citizen security' measures in cities across Latin America and the Caribbean, this paper offers some opportunities for renewing and revitalizing SSR. The emphasis of citizen security interventions on multiple forms of insecurity, data-driven and evidence-informed prevention, the promotion of social cohesion and efficacy and designing crime prevention into the social and built environment are all insights that can positively reinforce comprehensive SSR measures in the 21st century.SSR Papers provide innovative and provocative analysis on the challenges of security sector governance and reform. Combining theoretical insight with detailed empirically-driven explorations of state-of-the-art themes, SSR Papers bridge conceptual and pragmatic concerns. The series is authored, edited, and peer reviewed by SSR experts, and run in collaboration with the Geneva Centre for the Democratic Control of Armed Forces (DCAF). Through in-depth discussions of governance-driven reform SSR Papers address the overlapping interests of researchers, policymakers and practitioners in the fields of development, peace, and security.