The Costa Rican Payment for Environmental Services Program (PESP) was a pioneer programme to be developed using the notion of Environmental Services (ES). The PESP has been analysed as a very promising and innovating instrument for conservation purposes. As such, many scholars analysed the PESP and discussed its efficiency and its effects on poverty alleviation. In this chapter, we adopt an institutional framework to analyse the genesis and evolution of the PESP underlying the role of stakeholders. We show that PES governance is a social construction where many stakeholders are interacting to orient the objectives and functioning of the PESP towards their vision and interests. Indeed, the main decisions regarding the programme's features reflect the state and evolution of forest stakeholders' power balance and their learning process.