The terrestrial water cycle functions across multiple spatial scales simultaneously, linking together the dynamics of soil-plant-atmosphere (SPA) processes and controls. These processes include water transport within the vadose soil zone and between soil and root systems, transport within plant vascular systems, and plant or soil water exchange with the atmosphere. Controls on these processes depend on biotic and abiotic interactions as affected by climatic and edaphic conditions, as well as species-specific anatomical and physiological responses to their environments. Studies focused on specific ecohydrological processes or controls have broad applicability for modeling; however, resource limitations often prevent cohesive, multidisciplinary studies that span across the SPA continuum. As such, individual research can be quite disconnected from the entire SPA continuum, which can lead to incomplete or inappropriate analyses and thereby hinder development of critical elements in models, model refinement, and validation. This session strives to bring those researchers together to integrate current knowledge from different perspectives into a holistic picture that could ultimately enhance progress toward better regional or global models that rely on understanding water flux at various scales. The session talks will loosely follow mechanisms and controls of water flux from soils through plants to the atmosphere, including modeling talks that link together processes governing water flux across scales. The session will be informative for all those studying water flux from aspects ranging across cellular to ecosystem scales.