This working paper explores the linkage between security sector reform and development assistance in countering radicalization. It is argued that security is an essential prerequisite to sustainable development. The premise of this paper is that there are important security sector reform objectives that are essential in countering radicalisation through addressing many of the underlying root causes that can create and sustain radical opposition to authoritarian or totalitarian governments in developing countries. It is often the case that the security forces are themselves not so much guarantors of security but rather a key agent of insecurity in themselves. At its simplest security sector reform seeks to improve the professional capacity of the security sector while at the same time also seeking to ensure that it respects human rights and is not corrupt and properly accountable.