Recent and widespread tree mortality events caused by drought, insects, and pathogens are now occurring globally on every forested continent, and are anticipated to increase as temperatures rise with global change. Considerable research interest has been focused on the ecological causes and consequences of these events, which are often driven by the interaction of ecophysiological stress and biotic agents of mortality (insects and pathogens). Such attention is needed for fruitful improvement of predictions for the timing, extent, and severity of these events. Our current poor ability to predict when and where trees will die in response to climate stress and attack by tree pests and pathogens generates significant uncertainty over how global change will impact forests. Widespread tree mortality at a global scale is expected to have massive ecological effects on community composition, plant and animal habits, water resources, and even the potential to alter the planetary C cycle, reducing land surface C uptake and storage, and risking a transformation of these forests from C sinks to C sources. One of the leading uncertainties in correctly projecting global climate change is the uncertainty in anticipating climate change feedbacks on the global terrestrial C budget, in part due to potential increases in forest disturbance. However, improving predictions, and ultimately management actions that mitigate such disturbance, has been hampered by a predominately disciplinary research approach. Yet, tree mortality in most forests is driven by a combination of abiotic (climate stress) and biotic (insect and pathogen) interactions. Given the need to anticipate the effects of global change on forests, a cross-disciplinary approach to understanding the interactions of drought, pests, and pathogens will be necessary to develop predictive models of forest change in response to multiple drivers. In this session we aim to bring tree physiologists, forest entomologists, forest pathologists, and those working at the intersection of these fields together to share recent research results and interdisciplinary approaches to understanding tree mortality. We aim to challenge speakers to identify limitations that could be overcome with a cross-disciplinary approach. Speakers in this session will address: physiological tree stress on pest and pathogen defenses, insect-pathogen-plant interactions as drivers of climate-related tree mortality, ecosystem management where disease control is one factor in a multi-faceted management framework, drought effects on pathogen biology, signaling between defensive biochemical pathways and plant stress, and development of modelling approaches.