PROJECT SUMMARY Family formation processes, including marriage, contraception, and childbearing, are among the most im- portant factors shaping the health and wellbeing of families and children. The substantial, long-term conse- quences of the parental family for children's family formation outcomes are among the most well-documented forces of change in the social sciences. However, a powerful factor has been overlooked—parental mental health. Not only are mental disorders highly prevalent the world over, but parental mental disorders are known to have powerful consequences for children, likely to shape their later-life family formation processes. We will address this important gap in research by integrating parental mental disorders into intergenerational models of family formation using a 24-year, prospective family panel study. To advance knowledge of these intergenera- tional processes using these new measures, we aim to: (1) Generate the first estimates of the role of parental mental disorders in shaping their children's subsequent marriage, contraception, and childbearing; (2) Use DNA-based polygenic risk scores from mothers, fathers, and their children to assess omitted genetic variable bias in these intergenerational models; and (3) Create and evaluate new prospective measures of sexual risk- taking and substance use mechanisms likely to link parental mental disorders to their children's marriage, con- traceptive use, and childbearing. The results will provide three significant advances. One is the first general population investigation of the intergenerational influence of parental mental disorders on children's marriage, contraception, and childbear- ing. A second is the first study of the genetic contribution to the intergenerational influences of parental mental disorders on family formation. To date nearly all population models of intergenerational influences on family formation are forced to conclude that unobserved genetic similarities may account for observed associations. We will introduce a new generation of intergenerational research—designs that integrate genetic propensities. The third is a significant advance in our understanding of the role played by children's premarital sex, sex with- out contraception, and substance use in linking parental factors to children's family formation, as these events could mediate this relationship. These steps will significantly advance our understanding of the intergenera- tional influences on the dynamics of marriage, contraception, and childbearing, all of which are crucial for health and wellbeing.