Increases in emerging infectious diseases over the last few decades have caused global declines in biodiversity. Anthropogenic global climate change is predicted to influence human and wildlife disease dynamics worldwide, possibly exacerbating these disease-driven declines. One reason that climate change might affect disease dynamics is because the infectivity and virulence of pathogens, as well as host resistance and tolerance of infection can vary with climatic conditions. My research focuses on understanding how host thermoregulatory behavior and environmental temperature influence host disease susceptibility. Using individual-level laboratory experiments and global research synthesis, I demonstrate 1) how hosts use behavioral thermoregulation to boost disease resistance and 2) that the impact of environmental temperature on host susceptibility can be predicted by the host population’s adapted climate.