Contemporary water management practices worldwide are informed by two leading paradigms: integrated water resources management and adaptive management. While previous scholarship has already studied the two paradigms, as well as their central principles, in isolation, there are few attempts only to theorise their interaction and to explore empirically their parallel implementation and co-existence. This article contributes to this emerging literature. Its ambition is to review and complement current frameworks conceptualising the impact of integrated water resources management on adaptive capacity. To this end, the article analyses the involvement of non-state actors in United Kingdom water and flood risk management, specifically in England and Wales. This is an exciting case to study: for many decades, environmental management in England and Wales had a reputation for being a technocratic exercise. In the past 15 years, however, environmental authorities undertook major efforts to lay the foundations for enhanced collaboration and stakeholder participation, amongst others encouraged by two European Union initiatives reflecting integrated and adaptive management principles: the Water Framework Directive and the Floods Directive. The empirical evidence suggests a spurious link only between the two paradigms. This contradicts conventional wisdom which, so I argue, tends to oversimplify a complex relationship. I introduce three theory-informed arguments -relating to conceptual diversity, path dependency, and the nature of the dependent variable -to address these shortcomings and to contribute to theory building.