Recent research on ultimatum bargaining, the fact that children often confront and use ultimatums, and theories of developmental psychology all combine to suggest that studying children's ultimatum behavior will be particularly enlightening, both theoretically and with respect to the development of bargaining behavior. The results from two experiments indicate that younger children made larger offers and accepted smaller offers than older participants. Boys took greater strategic advantage of asymmetric information than girls; this dichotomy began with nine-year-olds (third graders) and continued for twelve- and fifteen-year-olds (sixth and ninth graders) as well as for college students. Like adults, children accepted smaller offers when they did not know how much was being divided. Older children required increasingly higher offers, except for college students who were willing to accept considerably less than others. Also, some of the nine-year-olds displayed an extremely strong sense of fairness. The discussion focuses on the development of bargaining strategies and concerns for fairness.