Amphibians are suffering population declines globally, and understanding how environmental parameters influence their thermal and moisture preferences and performance at various tasks is crucial to understanding how these animals will be influenced by climate change. Body temperature and hydration affect organismal performance at many fitness-related tasks. Since amphibians are ectotherms with highly water-permeable skin, environmental temperature and moisture directly affect their body temperature and hydration. Therefore, amphibians should select habitats with the optimal combination of temperature and moisture to perform tasks necessary for survival. However, interactions between environmental temperature and moisture can influence habitat selection and task performance in different and often unpredictable ways, and this has only infrequently been considered. We tested for interactions between environmental temperature, moisture, and organismal hydration on temperature and moisture preferences and jumping performance in Green Frogs (Lithobates clamitans) in the laboratory, using thermal and moisture gradients, and high-speed video and force plate data. We then integrated the lab experiments with field data. In the thermal and moisture gradients, frogs selected environmental conditions that minimized cutaneous evaporative water loss, hydroregulating more stringently than thermoregulating. These results are consistent with frogs in the field, which had highly variable body temperatures, but were always hydrated above 95% of their standard mass. However, conditions that minimized evaporative water loss frequently did not maximize jumping performance because warmer temperatures conferred greater performance. The ecology of L. clamitans may explain the discrepancy between their preferences and jumping performance optima because the frogs remain in wet environments that serve as refuges from dehydration. In parts of their range where frogs are subjected to warmer and drier conditions, they are likely to select microhabitats that minimize the risk of dehydration, possibly at the expense of their ability to forage and escape from predators.