Young toads were brought into the laboratory before hibernation in the autumn and exposed to alternating periods of low temperature and high temperature and feeding, thus simulating climatic cycles. In newly metamorphosed, non-hibernating toads, food intake was initially low and growth was stagnant, but subsequently food intake and lean growth increased strongly. Presumably, growth was initiated independently of feeding. In one-year-old, non-hibernating toads, food intake and growth declined with time, but high rates of feeding and growth were restored in the toads exposed to simulated hibernation. In both metamorphosed toads and one-year-old, hibernating toads, a period of predominant fat deposition succeeded predominant lean growth before food intake again declined to low levels. Initiation of sexual maturation in the female toads coincided with suspended growth, whereas sexual maturation in males was not correlated with changes in growth rate. In the female, but not the male toads, sexual maturation was greatly advanced under the experimental conditions, resulting in adult female sizes far below those typical of the wild population.