Clear changes occurred in the field of conventional arms control in the last two decades. States adopted a multitude of norms on especially small arms control in various multilateral control instruments. In addition, non-governmental advocacy actors often established themselves as active participants in control debates with governments. The changes are surprising because they took place in the security sphere and therewith in an area traditionally understood to be the exclusive domain of governments. This research project investigates the significance of the changes for the traditional understanding of security governance. Specifically, it investigates the emergence of control norms and the role and policy impact of non-governmental actors in the promotion of the norms. It asks whether the normative changes and significance of nongovernmental actors therein challenge the understanding of security governance that underpins many established approaches to international relations theory.