We conducted a systematic review of studies on the impact of payments for environmental services (PES) that set natural forest conservation as the goal on deforestation and poverty in developing countries. The review is motivated by debates over whether the pursuits of conservation and poverty reduction in developing countries tend to conflict or whether they might be complementary. A search for rigorous impact evaluation studies identified eleven quantitative and nine associated qualitative evaluation studies assessing the effects of PES. The methodological rigor of these studies varied widely, meaning that the evidence base for the impact of PES policies is limited in both quantity and quality. Given the evidence available, we find little reason for optimism about the potential for current PES approaches to achieve both conservation and poverty reduction benefits jointly. We call for the production of high quality impact evaluations, using randomisation when possible, to assess whether the apparent incompatibility of conservation and poverty reduction might be overcome through programming innovations.
