This publication continues efforts by the OECD’s Development Assistance Committee (DAC) to develop tools and instruments for conflict prevention and for improving security and stability in the long term.  The guidance underlines the positive role that the integrated reform of a country’s security system can play in stabilising fragile, conflict-prone or conflict affected states.  This includes not only the armed forces, police and gendarmerie, intelligence services and justice and penal systems, but also the civil authorities responsible for oversight and democratic control.Part I contains a policy statement and paper endorsed in 2004 by development ministers and agency heads of the DAC and by the OECD council. It sets out the key concepts of security system reform (SSR) and suggests ways to support it in developing countries, taking into account regional dynamics. In Part II, a lead consultant examines the origins of the SSR agenda and the challenges that donors face in promoting it in partner countries.  The Annex to the publication contains work by an expert working in each of the four regions: Africa, Asia-Pacific, Latin America and the Caribbean, and South-east Europe, the Baltics and the CIS.  It sets out their assessment of the changes that are taking place in the way that developing countries in these regions think about security and provides an account and analysis of individual reform activities currently being undertaken.