The Project for Ecosystem Services (ProEcoServ) is UN Environment’s flagship project focused on the valuation and mainstreaming of ecosystem services into policy design within the larger ambit of sustainable development. It builds on the Millennium Ecosystem Assessment (MA), its sub-global assessments, and the ongoing MA followup process. The project had pilots in four countries: South Africa, Trinidad and Tobago, Chile, and Viet Nam. During the four years of the project, ProEcoServ facilitated policymakers in pilot countries to access scientific information on how ecosystem services impact human welfare and economies. More importantly, ProEcoServ successfully demonstrated the processes for the uptake of ecosystem assessment policy tools by decision makers. This was achieved by developing tools and products to be used by policymakers, using ProEcoServ information to support key sector investment decisions and macro-economic models. Ultimately, ProEcoServ left a lasting legacy in the pilot countries in their spheres of governance, ranging from local, provincial, national and regional levels. The project was developed over a period of four years, 2011 to 2015, and implemented in four pilot countries, including South Africa, Trinidad and Tobago, Chile and Vietnam.