This chapter examines the ways law shaped procreative behaviour in the Roman world. As in classical Athens, Roman society was one in which marrying and having legitimate children to continue the line was fundamental, legally recognized and elaborated as such. In Rome, more particularly, the male head of the household enjoyed greater flexibility in ‘constructing kinship’, and planning for inheritance and succession, than in most legal systems. Divorce, remarriage and adult adoption were all integral to the enterprise, as well as considerable testamentary freedom, especially for women. Concern to produce legitimate children went beyond individual families, moreover, and the emperor Augustus legislated to promote marriage and childbearing, while Trajan adopted a financial approach, providing material rewards, allowances for children, in Italy. This chapter argues against the tendency in the modern scholarship to see Augustus’ aims as either demographic or moralistic: in the ancient world, encouraging procreation and restoring public morals went hand in hand. Nor should the apparent failure and unpopularity of the laws detract from the importance of the project: marriage and children are crucial to a community and one job of any good ruler is to emphasize that point.