As climate change will affect thermal environments and physiological performance of ectotherms, it is critical to understand their thermal ecology. One group of ectotherms with poorly understood thermal ecology is ambystomatid salamanders of central Mexico. We studied water temperature selection in the endangered, endemic salamander species Ambystoma altamirani in the field and in a laboratory thermal gradient. Mean field water temperature was 14.9 °C, with males found at cooler water temperatures than females and juveniles. Mean final selected temperature in the laboratory thermal gradient was 26.3 °C, with males selecting the lowest temperature and females the highest. The difference between laboratory-selected water temperature and field water temperature suggests that A. altamirani may have some capacity to respond to climate change, but more investigations of their thermal physiology are needed.