In Experiment 1, parents of preschool, first, and sixth grade children were asked to make judgments regarding situations in which they would wish their child to behave prosocially. Factors relevant to three sources of influence, including characteristics of the situation, recipient, and donor, were examined. Ten help ing and 10 sharing opportunities, ordered from high to low cost, were presented. Eleven potential recipients at four age levels (younger, same age and older chil dren, and adults) and three familiarity levels (unknown, familiar, or family mem bers) were suggested for each prosocial opportunity. Parental limitations on chil dren's altruism were a direct function of the situational cost involved and the age and familiarity of the recipient. A second experiment largely replicated the main effects and simple interactions obtained in the first experiment. In addition, in terviews conducted with the parents who participated in the second experiment revealed that parents had cogent rationales to support the limitations they im posed on children's altruism. These rationales and the implications of parents' limitations on children's altruism for natural acquisition of prosocial behavior and for prosocial training programs are described.