This study examined how a major life stressor--the transition to parenthood--affects marital satisfaction and functioning among persons with different attachment orientations. As hypothesized, the interaction between women's degree of attachment ambivalence and their perceptions of spousal support (assessed 6 weeks prior to childbirth) predicted systematic changes in men's and women's marital satisfaction and related factors over time (6 months postpartum). Specifically, if highly ambivalent (preoccupied) women entered parenthood perceiving lower levels of support from their husbands, they experienced declines in marital satisfaction. Women's ambivalence also predicted their own as well as their husbands' marital satisfaction and functioning concurrently. The degree of attachment avoidance did not significantly predict marital changes, although women's avoidance did correlate with some of the concurrent marital measures. These findings are discussed in terms of attachment theory.