The responses of 2- and 8-day-old rats (Rattus norvegicus) and hamsters (Mesocricetus auratus) to thermal stimulation were assessed in 4 experiments. In Experiment 1, the surface underlying the pup was cooled, and the latency to escape to a region of warmth was measured. Experiment 2 required pups to locomote farther to gain access to warmth. Experiment 3 was similar to Experiment 1 except the underlying surface was heated. Finally, in Experiment 4, locomotor behavior was assessed during isothermal cooling in which there was no possibility for escape. In general, hamsters exhibited more rapid and robust responses to thermal stimulation than rats. A framework for interpreting these results is presented emphasizing how differences in locomotor and thermogenic capabilities influence thermoregulatory behavior under different task conditions.