Abstract (1) We tested the hypothesis that contact behaviour in Adélie Penguin ( Pygoscelis adeliae) chicks of crèching age is strongly influenced by thermoregulatory demand. (2) Estimated thermoregulatory costs (% minimal metabolic rate) for early crèche stage (1 kg) chicks were much higher (13.4–121.0%) than for late crèche (3 kg) chicks (0–45.1%). The incidence of contact behaviour was high during early crèche, but uncommon during late crèche. (3) Both the percentage of early crèche chicks forming contact groups and the mean number of chicks per group increased significantly as thermoregulatory demand increased. (4) Thermoregulatory costs were significantly higher when late crèche chicks exhibited contact behaviour than when they did not. (5) Contact behaviour in Adélie Penguin chicks therefore appears to perform a thermoregulatory function and probably confers important energy savings in terms of maintaining a favourable daily energy budget and maximum fasting duration.