Inbred strains of mice exhibit different patterns of maternal behavior, providing material for studies of genetic influences on the expression of maternal behavior. Beginning 1 day after birth, maternal behavior was recorded daily for 14 days in the first and second litters of C57BL/6J (B6) and DBA/2J (D2) mothers. D₂ mice had higher pup survival than B6 mice, and pup survival was higher in both strains in second litters than in first litters. D₂ mothers spent more time engaged in maternal behavior, especially resting with, crouching over, and nursing pups than B6 mothers with first litters, but not with second litters. Not all measures of maternal behavior were correlated with pup survival; with both litters, B6 mothers retrieved pups faster than D₂ mothers.