The PES primer is designed to provide the reader with a solid understanding of payments ecosystem service (PES) and markets and the mechanisms of PES deals, and based on this aims to provide guidance for developing PES deals. The first section provides an introduction to ecosystem services and markets and payments for ecosystem services as well as a detailed review of basic PES types and concepts with examples. The second section informs about the potential PES deals offer to the poor population by reflecting opportunities and risks as well as ideal conditions for such schemes. The third section is the core part that includes a step-by-step approach for the development of PES deals, for identification of ecosystem service prospects and research potential buyers, assessment of institutional and technical capacity, structure of agreements, and implementation of PES agreements. The section is complemented by numerous case studies. The final section concludes on the importance of honest brokers for enabling pro-poor PES to reach those who most need it.