This study assesses the impacts of the payments for environmental services (PES) programme in Costa Rica in relation to reforestation activities for the establishment of carbon sinks. The methodology used is the Sustainable Livelihoods Approach (SLA), which is based on five assets: financial, human, social, physical and natural. The study shows that the PES programme has had a significant impact on financial assets, not so much through the payments themselves but from the income expected from timber sales. The payments have acted as a catalyst for reforestation programmes, covering some of the initial outlay. However, the high transaction costs and obstacles to joining the scheme can preclude access to the PES for some of the most vulnerable groups who are dependent on other government programmes for their survival (e.g., peasants in receipt of housing support). There have been important benefits in terms of human assets through the provision of technical assistance and through 'learning by doing', particularly in relation to reforestation. The PES programme has had a considerable impact on social organisation, encouraging alliances between NGOs and providing the financial and human capital to consolidate objectives in organisations working with small producers. There has been a positive impact on the recovery of forest landscapes in the area, contributing to improvements in natural assets, which in turn has brought benefits for tourism. There have also been negative effects, particularly in relation to physical assets, including the deterioration of existing infrastructure such as roads and bridges, through increased use.