Payment for ecosystem services (PES) has been widely promoted as an effective and efficient model for conservation; however, few studies have empirically examined how the market-based approach interacts with farmer's decision-making processes and their abilities to sustain new conservation practices. This paper examines the sustainability of a PES silvopastoral programme in Colombia from peasant farmers’ perspectives. Programme participants were asked questions regarding their perceived ability to continue with the silvopastoral practices, the influence of the economic benefits and contracts on behavioural change, and the programme's impacts on self-determination, innovation and social learning; factors considered critical for sustained resource management. While the participants expressed a need for the PES programme practices, less than half stated that they would continue with the silvopastoral measures and only 13% understood that part of their contractual commitment was to conserve forests. Ten per cent of the participants considered themselves the principal decision-maker in the farm-level changes and only one participant had altered the prescribed practices, despite a common perception that some techniques were not suitable for the region. The results suggest a need to re-examine the degree to which the PES model in fact encourages adaptive management practices and sustained land-use behaviours in peasant communities.