Mercury is an atmospherically transported contaminant found even in relatively pristine habitats. Once accumulated at the base of the food web, mercury can move between animals that are linked trophically. Pond-breeding amphibians may be particularly important vectors of mercury flux from remote freshwater to terrestrial systems because they feed on algae and detritus as tadpoles and metamorphose into insectivorous terrestrial adults where they carry out most of their remaining life cycle. However, it is still unclear how mercury concentrations change across life stages in complex life cycle amphibian species. The data presented here includes total mercury (THg), methylmercury (MeHg), and isotopic composition (δ13C, δ15N) in boreal chorus frogs (Pseudacris maculata) at two subalpine ponds in the Rocky Mountains, CO, USA. We sampled various life stages including breeding adults, eggs, tadpoles, metamorphs, and mid-summer adults.