Increasing salinity levels are an important threat to many freshwater ecosystems. In coastal freshwaters, transient increases in salinity can result from coastal flooding and storm surge, enhanced by climate change and rising sea levels. Phenotypic plasticity can enable organisms to respond adaptively to changing or unpredictable conditions, and many examples of plasticity involve shifts in developmental trajectories, including altered rates of growth and development. Amphibian larval development provides an excellent opportunity to study such developmental plasticity. In high quality environments, larval amphibians are predicted to reduce developmental rate in order to reach maximum size at metamorphosis, while in poor environments with slower growth, individuals are predicted to accelerate development in order to metamorphose as early as possible, resulting in smaller size at metamorphosis. When the quality of the environment changes during development, larval amphibians may be able to shift developmental trajectory, even accelerating growth rate enough to compensate for earlier growth suppression. In an experiment with toad tadpoles, we investigated plasticity in growth and development during and after exposure to elevated salinity during different portions of larval development. We predicted that growth rates would be more plastic early in development and that developmental plasticity would be constrained during both early and late developmental stages and thus apparent only during mid-development. In addition to providing insights into the capacity for adaptive developmental plasticity in larval amphibians, our results will also help evaluate potential impacts of salinity changes in freshwater habitats.