The CGIAR Systemwide Program on Collective Action and Property Rights (CAPRi) is an initiative of the 15 centers that belong to the Consultative Group on International Agricultural Research. The initiative promotes comparative research on the role played by property rights and collective action institutions in shaping the efficiency, sustainability, and equity of natural resource systems. CAPRi's Secretariat is hosted by the International Food Policy Research Institute's (IFPRI) Environment and Production Technology Division (www.ifpri.org. CAPRi Working Papers contain preliminary material and research results and are circulated prior to a full peer review in order to stimulate discussion and critical comment. It is expected that most Working Papers will eventually be published in some other form, and that their content may also be revised.