Yellow-legged frog tadpoles graze on algae and diatoms. They breed and lay eggs at high elevations in shallow water. Breeding does not begin until ice is absent from lakes and streams. Clusters of eggs are laid and usually attached to rocks and gravel. Clusters can contain up to 500 eggs, usually averaging about 200 per cluster.
Major predators are garter snakes and introduced trout.
Yellow-legged frogs compete for food and space with pacific tree frogs. The extirpation of introduced trout from high-mountain streams is the most important conservation action for this species. A little over one third of their potential range is at extreme fire risk.