Snow-dominated mountain regions are strategic providers of water resources and ecosystem services. They are also likely to be highly vulnerable to a warming climate. In this review, we argue that an ecohydrologic perspective is critical for understanding changes that are already occurring and ultimately for predicting future vulnerabilities in both water resources and ecosystem health. We focus our review on the relatively well-studied mountains of the Western USA. In this region, observations and models show significant climate-driven changes to hydrologic processes including changes to snow accumulation and melt, evapotranspiration, soil moisture, and streamflow. At the same time, there is growing evidence of climate-driven changes in vegetation structure and function. We summarize these studies and discuss how changes in hydrology interact with changes in terrestrial ecosystems to lead to complex and sometime synergistic responses. We conclude by identifying research needs to be addressed by emerging monitoring and synthesis networks that focus on the ecohydrology of mountain environments within a changing climate.