Studies of the impact of environmental contaminants on reproduction have typically focused on effects on fertility and subsequent reproductive failure. Contaminants may also impact reproductive output or other aspects of life history through effects on resource acquisition or allocation. We fed successfully breeding female white-footed mice (Peromyscus leucopus) diets containing polychlorinated biphenyls (2:1 Aroclor 1242:1254) at levels of 0 (n = 10), 10 (n = 12), and 25 (n = 10) ppm (mg polychlorinated biphenyls [PCBs]/kg food). After 4 months on the diets, female mice were bred with male mice maintained on control food. There was no effect of PCB exposure on litter size at birth or weaning, although fewer female mice on the 25-ppm diet gave birth. There was no effect of PCB dose on maternal metabolic rate at peak lactation or on total food (dry matter) intake during lactation. Female mice on the 10-ppm diet, however, consumed more food per pup during lactation and weaned larger pups, although these differences disappeared after 4 weeks of age. We conclude that although moderate-term exposure to PCBs did decrease the number of litters produced for high-dose female mice, it did not change litter size, pup growth rate, or energetic measures for those female mice that did successfully reproduce.