The ways plants use – and conserve – water has myriad functional implications for plant fitness, drought responses, ecosystem functioning, and large scale climate feedbacks. Recently, there has been a surge of research toward quantitatively classifying plant water use strategies (e.g., isohydry and anisohydry, safety vs. efficiency) to understand their interactions with hydraulic traits or other key physiological processes. This work has illuminated the coordination between plant water use and carbon uptake that mediate drought stress responses, including mortality. Promisingly, these strategies appear to be applicable at broader spatial scales and thus provide an exciting new way to predict the responses of ecosystem water and carbon fluxes to increasing levels of water stress. However, the appropriate metric and timescales used to characterize plant water use strategies remain a matter of debate. This session promotes research on classifying plant water use strategies and understanding the implications of these strategies for plant functioning at spatial scales ranging from leaves to whole ecosystems. By investigating plant water use strategies with a diverse array of experimental, observational, and modelling approaches, the speakers in this session will seek to identify the successes, disagreements, and ways forward in plant water use research.