In 2004, the UN Security Council adopted Resolution 1540, which mandates a comprehensive set of supply-side controls on all States. Since then, governments have worked to varying degrees to ensure compliance with the terms of the Resolution; yet, for a variety of reasons ranging from abject disinterest to a vexing lack of capacity, progress on implementation has been uneven. In this report Managing Across Boundaries Managing Director and Senior Associate Brian Finlay argues that while the 1540 mandate is ultimately the responsibility of national governments, in some cases, civil society, think tanks, and other academic and educational institutions with specialized expertise can expand their efforts beyond just advocacy in supporting States in their compliance efforts. Examples of civil society engagement may ultimately include undertaking legal gap analyses, conducting targeted training, the provision of specialized expertise, financial assistance, building implementation networks, the identification of external donors, coordinating regional cooperation, and/or the sharing of best practices across national boundaries.