The existing literature on marriage and fertility decisions pays little attention to the roles played by risk preferences and uncertainty. However, given uncertainty regarding the availability of suitable marriage partners, the ability to contracept, and the ability to conceive, women’s risk preferences might be expected to play an important role in marriage and fertility timing decisions. By using data from the Panel Study of Income Dynamics (PSID), I find that measured risk preferences have a significant effect on the timing of both marriage and fertility. Highly risk-tolerant women are more likely to delay marriage, consistent with either a search model of marriage or a risk-pooling explanation. In addition, risk preferences affect fertility timing in a way that differs by marital status and education, and that varies over the life cycle. Greater tolerance for risk leads to earlier births at young ages, consistent with these women being less likely to contracept effectively. In addition, as the subgroup of college-educated, unmarried women nears the end of their fertile periods, highly risk-tolerant women are likely to delay childbearing relative to their more risk-averse counterparts and are therefore less likely to become mothers. These findings may have broader implications for both individual and societal well-being.