Abstract Geologic, geomorphic, hydrologic, ecological, and biogeochemical conceptual models of river floodplains developed since the mid‐20th century led to the current conceptualization of floodplains as integrative systems that store and transform diverse materials, provide a source of material that can be transported downstream, and function as ecosystems. Scientific recognition of floodplains as a critical component of river corridors is not, however, matched by societal perceptions and legal or regulatory frameworks, which typically treat the active channel and floodplain as separate entities. The development of an integrative scientific understanding of floodplains is reviewed here, along with five primary challenges to progress in understanding and managing floodplains. These challenges involve: integrating thinking, data collection, modeling, and prediction across disciplines in a manner that facilitates the work of practitioners and regulators; scaling across time and space; measuring and predicting feedbacks and nonlinear interactions; measuring and predicting resilience and resistance of floodplains and river corridors to natural and human‐induced disturbances; and effectively communicating social and technical uncertainties in river management.