Gravid female golden-mantled ground squirrels, Citellus lateralis, were kept at 7 °C in 6 h light (L): 18 h dark (D) and 18 h L: 6 h D regimes. Young born and raised under these conditions were sacrificed at 5 months of age. Total ether-soluble lipids were significantly greater and basic weights (fat-free, water-free weights) were significantly less for young raised in the 6 h L: 18 h D regime. Live weights of the two groups did not differ. The adult females did not appear to respond to the different light schedules, with no significant differences noted in either the basic weights or lipid indices. It is suggested that (1) shortened days promote fat deposition and thereby could influence the time of onset of hibernation in young of this species, and (2) the adiposity of an animal is not necessarily correlated to the live weight.