Introduction In December 2009, the UN General Assembly voted to start negotiations to achieve an international Arms Trade Treaty (ATT) by 2012, to create international standards governing the global conventional arms trade. While the details of an ATT are still to be negotiated, it is clear that such a treaty will be implemented at the national level, and thus will require that all countries have in place a national system for the licensing and control of international transfers of conventional arms. There is no ‘one size fits all’ solution. The systems of individual countries will be based on the extent and nature of their arms trading, as well as their system of government, technological infrastructure, capacity, and legal tradition. The practical guide draws out the core principles and elements from different systems and gives examples from a number of different countries to demonstrate how these are implemented. The guide is intended to provide a framework for how states can adopt a functional and effective national control system.