This StoryMap compiles information about post-fire tree mortality based on past and current research efforts at the U.S. Forest Service Rocky Mountain Research Station, Missoula Fire Sciences Laboratory. It is divided into five main sections that provide basic information on how fires kills trees, how to predict post-fire tree mortality, a database of tree mortality records after fire, model accuracy, and decision support. By killing trees, wildland fires influence ecosystems in many ways, including limiting ecosystem productivity, altering resource availability, and changing the structure and composition of vegetation. These changes can have both positive and negative impacts on carbon storage, biodiversity conservation, hydrologic processes, and economic and social services. In fire-adapted and fire-dependent ecosystems, fire controls tree density and species dominance, creating habitat that supports diverse plant and animal species that cannot persist in the absence of fire. However, fire-adapted ecosystems may be vulnerable to climate-driven alterations to fire regimes that have been an emerging threat in recent decades, with observations of increasing fire size, frequency, and severity. Climate-mediated increases in fire severity and frequency are projected to cause large decreases in carbon stocks through loss in forested area, and increased fire frequency is killing trees before maturity. Such changes in fire regimes can shift forests to non-forested states. These impacts make understanding fire caused tree mortality essential to predicting fire effects from local to global scales.