This dissertation is comprised of three papers that examine the implications of unintended fertility and nonmarital conceptions on adult and child well-being. The first paper examines the role of pregnancy intentions on parents' psychological wellbeing. Using two waves of data from the National Survey of Families and Households (NSFH) (n = 825 women, n = 889 men), this study finds that unintended births are associated with increased depressive symptoms among fathers, and decreased happiness among mothers, even after accounting for relationship status and measures of psychological well-being prior to the birth. The second paper examines the relationship between pregnancy intentions and several metrics of child well-being over the life course (ages 0-30). This study uses longitudinal data from the NLSY79 (n = 22,247 person-year observations) and propensity score techniques to address limitations of prior research. Results indicate that children resulting from unintended pregnancies had a less emotionally supportive home environment compared to children resulting from intended pregnancies, even after accounting for the mother's marital status at birth and other characteristics associated with selection into unintended childbearing. Children resulting from unintended pregnancies also experienced more depressive symptoms as adults, which suggests that unintended birth may have long term consequences. The third paper examines the implications of nonmarital conceptions and subsequent patterns of relationship formation for child well-being. Postconception cohabitations, which are formed after the conception of a child but prior to birth, are an increasingly common response to nonmarital pregnancies, yet little is known about how children fare in this type of family structure. Using data from the Fragile Families Child and Well-Being Study (n = 8,218 personyear observations), this study found that children born to postconception cohabitors fared slightly better than children born to unpartnered parents, worse than those born to pre- and postconception married parents, and similarly to those born to preconception cohabitors in terms of economic resources, father involvement, and family stability. Despite these disparities, they had similar behavior problems and cognitive test scores compared to children in other family structures. Results suggest that the increase in postconception cohabitation is unlikely to be associated with consequences for child development, but may be linked to family instability and limited economic resources.