Finally Costa Rica, Mexico and Ecuador thank PROFOR, the World Bank Institute, and the Forest Carbon Partnership Facility in the World Bank for financing the project and sponsoring this report. * While no uniformly-agreed definition of PES exists, a widely-cited definition proposed by Wunder (2005) stipulates that PES is: "(a) a voluntary transaction where (b) a well-defined [environmental service (ES)] (or a land-use likely to secure that service) (c) is being 'bought' by a (minimum one) ES buyer, (d) from (minimum one) ES provider, (e) if and only if the ES provider secures ES provision (conditionality)." While conservation incentive payments may be conditional upon conservation activities or even outcomes, they are not conditional on provision of ecosystem services, and so do not strictly fit within this definition. Brief synopsis of the country programs Costa Rica and Mexico have been pioneers in the creation of PES mechanisms. Costa Rica started its PES Program (PSA) scheme in 1997, coordinated by the National Forestry Financing Fund (FONAFIFO) with funds from a tax on fossil fuels. By 2009, there were 671,000 hectares under the PSA. This helped increase national forest cover from 44% in 1998 to 51% in 2005. Costa Rica's experience is also notable as regards establishing an enabling policy, legal and institutional framework for PES. Mexico started its Hydrological Environmental Services Program (PSAH) in 2003 with earmarked funds from national water fees. The PSAH involved payments to landowning 'ejido' and 'agrarian communities', as well as individual landowners, for maintaining forest in hydrologically important areas. In 2004, the Payments for Carbon and Biodiversity Services Program (PSA-CABSA), which includes agroforestry systems, was added. These programs, both managed by the National Forest Commission (CONAFOR), have since been integrated into the Program of Payments for Environmental Services (PSAB). PSAB currently covers 2.2 million hectares of forest. More recently, Ecuador created the Socio Bosque program of conservation incentives in 2008. In addition, in June 2009 the Ministry of Environment established the "Páramo Chapter" of Socio Bosque resulting in the additional conservation of about 18,000 hectares of this Andean ecosystem of great importance for protecting and regulating water resources. By 2011 about 868,000 hectares of native forest and other priority ecosystems were protected.