Our modern security systems have recently come under a lot of criticism: as too bureaucratic and unadaptable, too secretive and untrustworthy, and too obsessed with information technology rather than human needs. Yet listing failures is easy; security is never perfect. The question is why current approaches fail and whether there are viable alternatives. The root of their shortcomings is in the interaction of the very pillars of our security system in the contemporary context. While our enemies have adopted the technologies of the Information Age, changing how they organize and fight, these same technologies have only created more vulnerabilities for states. Governments have been generally unwilling to maximize their use of these technologies because it would require the wider release of information and the opening of organizational structures to include society in security making. Yet countering diffuse modern threats striking deep into our states and across our economies requires mobilizing the diffuse skills and variation of modern society. Open approaches for mobilizing participation and coproduction have the capabilities needed to improve contemporary security policy making, problem solving, and provision. Moreover, open participatory security can be effective not only for technical security, but also for restoring trust among the citizens and rebuilding the legitimacy of the state.