The World Food Summit (Rome, November 1996) recognized the urgency of improving the information available to governments, their international partners and all members of civil society in every country, in order to guide their actions against food insecurity and to make them as effective as possible. As a result, in 1997 the FIVIMS (Food Insecurity and Vulnerability Information Mapping System) initiative was launched as a co-operative venture, with secretariat functions being assured by FAO, among about twenty multi- or bi-lateral organizations, inter- or non-governmental organizations, in order to assist countries and the international community to identify the “who, where and why” threatened by food insecurity. Even before the Summit, many countries had established approaches for this purpose based on multidisciplinary networks, at national and local levels. One of these approaches, developed first in French-speaking Africa, and with which FAO has accumulated a rich experience from its support and participation, is the FSIEWS method (Food Security Information and Early Warning System) proposed in this handbook as one of the tools available to those engaged in the fight against hunger. This contribution to the FIVIMS initiative is addressed to the national technical officers at central and decentralized level, as well as to their collaborators from the technical assistance community. The handbook aims to propose both a way and a set of tools which can be used at different stages.