To predict community-level responses to climate change, we must understand how variation in environmental conditions drives changes in an organism's ability to acquire resources and translate those resources into growth, reproduction, and survival. This challenge can be approached mechanistically by establishing linkages from biophysics to community ecology. For example, body temperature can be predicted from environmental conditions and species-specific morphological and behavioral traits. Variation in body temperature within and among species dictates physiological performance, rates of resource acquisition, and growth. These ecological characteristics, along with population size, define the strength with which species interact. Finally, the direct (individual level) and indirect (community level) effects of temperature jointly determine community structure. This mechanistic framework can complement correlational approaches to better predict ecological responses to climate change and identify which characteristics of a species or community act as leverage points for change. Research priorities for further development of the mechanistic approach include documentation and prediction of relevant spatial and temporal variation in body temperature and the relationships between body temperature, individual performance, and interspecific interactions.