Several studies have demonstrated important effects of parents’ childbearing behavior on their children’s childbearing preferences and behavior. The study described here advances our understanding of these family influences by expanding the theoretical model to include parental preferences, siblings’ behavior, and changes in children’s preferences through early adulthood. Using intergenerational panel data from mothers and their children, we test the effects of both mothers’ preferences for their own fertility and mothers’ preferences for their children’s fertility. Although both types of maternal preferences influence children’s childbearing preferences, mothers’ preferences for their children’s behavior have the stronger and more proximate effects. Mothers’ preferences continue to influence their children’s preferences through early adulthood; siblings’ fertility is an additional determinant of children’s family size preferences.