How technology and community organizing can combine to help prevent violence, with examples from Chicago to Sri Lanka. Tunisian and Egyptian protestors famously made use of social media to rally supporters and disseminate information as the “Arab Spring” began to unfold in 2010. Less well known, but with just as much potential to bring about social change, are ongoing local efforts to use social media and other forms of technology to prevent deadly outbreaks of violence. In The Technology of Nonviolence , Joseph Bock describes and documents technology-enhanced efforts to stop violence before it happens in Africa, Asia, and the United States. Once peacekeeping was the purview of international observers, but today local citizens take violence prevention into their own hands. These local approaches often involve technology—including the use of digital mapping, crowdsourcing, and mathematical pattern recognition to identify likely locations of violence—but, as Bock shows, technological advances are of little value unless they are used by a trained cadre of community organizers. After covering general concepts in violence prevention and describing technological approaches to tracking conflict and cooperation, Bock offers five case studies that range from “low-tech” interventions to prevent ethnic and religious violence in Ahmedebad, India, to an anti-gang initiative in Chicago that uses Second Life to train its “violence interrupters.” There is solid evidence of success, Bock concludes, but there is much to be discovered, developed, and, most important, implemented.