This article investigates the mass media as a social change that shapes individual behavior primarily via ideational mechanisms. We construct a theoretical framework drawing on social demography and social psychology to explain how mass media may affect behavior via attitudinal change. Empirical analyses of 1,091 couples in the Chitwan Valley Family Study, using detailed measures of social change from rural Nepal, show that exposure to the mass media is related to childbearing behavior, and to preferences for smaller families, weaker son preferences, and tolerance of contraceptive use. This result should motivate greater research attention to the influence of changing ideas on behavioral changes, particularly in the study of families.