This new edition of the Macrothesaurus for Information Processing in the field of Economic and Social Development represents a continuation of the combined efforts of many organisations over a period of almost 30 years to create a common vocabulary to facilitate the indexing, retrieval and exchange of development-related information. The Macrothesaurus comprises descriptors (keywords) designed for indexing books and documents covering the field of economic and social development. It can also be used as a search aid for documentation centres, libraries, databases and on-line networks. Efforts have been made to improve the user-friendliness and flexibility of the Macrothesaurus by increasing the number of non-descriptors (i.e. cross-references) and scope notes in this edition. The preparation of this fifth edition was guided by an Advisory Committee composed of representatives from the International Development Research Centre, Ottawa, the United Nations Department of Economic and Social Affairs, New York, the Organisation for Economic Co-operation and Development (OECD), and the OECD Development Centre, Paris.