Northern leopard frogs (Rana pipiens) were exposed to environmentally relevant concentrations of copper in water (control and 5, 25, and 100 microg/L, as CuSO4) in a static renewal system for 154 d from posthatch stage to metamorphosis. After 10 d of copper exposure (from Gosner stages 19-25), survival of tadpoles was not significantly different between treatments (averages range from 96.7 to 99.3%), but a significantly higher incidence of deformities (p < 0.05) was observed in the 100-microg/L treatment. Tadpole growth rate was decreased in the 25- and 100-microg/L treatments relative to controls. Tadpole survival, swimming performance, percent metamorphosis, time to metamorphosis, and survival during and time required for tail resorption were also negatively affected in the 100-microg/L treatment. Copper concentrations in tadpole tissues ranged from 46.5 to 769.5 mg/ kg dry mass and were positively related to copper concentrations in the water. In conclusion, copper was shown to affect development, growth, survival, and behavior in larval northern leopard frogs at ecologically relevant concentrations. The existing U.S. Environmental Protection Agency freshwater-quality chronic criterion for copper appears to be protective for larval Rana pipiens.