This paper investigates the reciprocal relationships between parents' attitudes and their children's behavior by focusing on attitudes toward nonmarital cohabitation and experience with cohabitation and marriage. The authors test hypotheses predicting that parental attitudes influence their children's behavior and that children's behavior alters their parents' attitudes. They use data from an intergenerational panel study of mothers and their children to specify models testing these predictions. Their findings support the hypotheses that (1) parental attitudes toward cohabitation influence children's behavior after controlling for children's own attitudes and (2) children's behavior influences their parents' attitudes. The empirical results also shed light on gender differences in the links between attitudes and behavior and possible causal links between aggregate level trends in family formation attitudes and behavior.