The principal, over‐arching aim of any catchment management work is to improve the water quality in our freshwater ecosystems and to make a significant contribution to their attainment of good ecological status in accordance with requirements of the EU Water Framework Directive. It is therefore vital that sufficient evidence is collected to provide an objective and robust assessment of the improvements delivered. In this review we explore the data and evidence available, which, taken together, demonstrate qualitatively and quantitatively that the delivery of integrated catchment management interventions can realise genuine improvements in water quality. To support the evidence collected, we have also summarised a number of case studies which demonstrate catchment management in action.