This chapter examines effects of partners' family values on the birth of their first or second child and the effects of parenthood transitions on changes in parents' family values. I use panel data from the U.S. National Survey of Families and Households, which includes parallel indicators of family values in both waves (1987-88 and 1992-94). Four dimensions of family values are examined: gender-role traditionalism, sexual conservatism, conjugal familism, and extended familism. The results provided only moderate support for the processes of values selection and values adaptation associated with first- or second-time parenthood. Although family values influenced the risk of having a first child, only women's conjugal familism and men's extended increased the risk, as hypothesized. Women's extended familism reduced their risk of becoming mothers between interviews. Effects of these values were quite substantial, increasing or decreasing the risk of having a child by as much as 40 percent. Neither men's nor women's values influenced the risk of having a second child. Values adaptation was reflected in the positive effects of first-time motherhood on women's conjugal familism and on both partners' extended familism. First-time fatherhood appeared to challenge men's gender-role traditionalism, however. Estimated effects of these major life transitions on family values were quite small, shifting parents less than 5 percent of the distance between the least and most traditional family values.