Diffuse pollution from agriculture is one of the most significant and difficult problems that has to be addressed under the Water Framework Directive (WFD). Although understanding continues to improve, it is still a highly complex problem that is surrounded by many uncertainties. Uncertainty relates to the basic biogeochemical process of pollutant mobilisation, transport and deposition, the effectiveness and costs of mitigation measures, the accuracy of catchment models and predictions, and also the attitudes and responses of farmers and other land users to policy interventions. Further complexity and uncertainty is added because efforts to understand and control diffuse pollution must be aimed at multiple spatial and temporal scales within an integrated catchment management (ICM) framework. The paper reviews the current state of knowledge regarding diffuse pollution mitigation and ICM. It is concluded that diffuse pollution from agriculture is 'manageable' in the sense that a balance between the ecological health of receiving waters and the transfer of particulates and dissolved material can be achieved in the future. However, this will require a new and distinctive approach to science, policy and practice that is both adaptive and collaborative in style.