The Theory publication and the companion on the practice of compiling consumer price indices (CPIs) is jointly published by the member agencies of the Inter-Secretariat Working Group on Price Statistics (IWGPS): the Statistical Office of the European Union (Eurostat), the International Labour Organization (ILO), the IMF, the Organisation for Economic Cooperation and Development (OECD), the United Nations Economic Commission for Europe (UNECE), and the World Bank. The IMF managed the update of the Theory publication and the CPI Manual. Drafting of this publication was led by Erwin Diewert with support from various authors. The Theory publication will be translated into Spanish, French, Arabic, and Russian.