In a laboratory experiment, we investigated the effects of low pH environment, a key parameter of acidity, on mortality, growth, and development in two populations of Rana temporaria that differ in the pH of their breeding ponds. In a population with pH neutral breeding sites, low pH treatment caused a prolongation in embryogenesis and an increased embryonic mortality, a higher proportion of deformed hatchlings and an increased larval time. Embryos and larvae from a population that was exposed naturally to low pond pH were more pH tolerant, as the only effect of low pH was increased larval time.