This publication summarizes the investments of the Global Environment Facility (GEF) since its inception in projects involving Payment for Ecosystem Services (PES). The following review is based on an analysis of 57 GEF projects in which PES is the core objective of the project or there is an explicit PES component/subcomponent in the project’s design. These 57 projects were chosen through a screening of the results frameworks of more than 500 GEF projects in GEF-1 to –5, which were in turn selected from the GEF Project Management Information System (PMIS) using key words closely related to PES. The 57 projects include most of those in the FAO publication (FAO 2007), the review of the financial mechanisms in GEF Land Degradation projects (Reed 2009), and those either listed by the GEF Agencies on their web sites (World Bank) or provided by the agencies for the purpose of this review (UNEP’s Division for GEF Coordination). This report does not cover GEF investments in financial mechanisms such as trust funds, ecotourism or certification schemes, unless there is an explicit reference to PES.