Does the Law influence population dynamics such as fertility and family time use patterns? If so, why, and how does this happen? These are the main questions this dissertation tackles. In doing so, a new wholistic approach to the use of Law in population studies is introduced, “Law and Demography”, contributing both theoretical and empirical elements to this scholarly sub-field. A theoretical contribution is made by embedding legal scholarship and theory of legal change into current demographic theory, thereby creating a new analytical space for Law in population studies. An empirical contribution is made by introducing the importance of context into the study of Law and populations. To fully understand the influence of a law, The Law must be considered in its correct topical and spatial context. The topical context is necessary as Law is a patchwork of interlinking edicts that are created and adjusted in relation to each other. Spatial context is crucial, as Law is heavily influenced by its surrounding environment, on the micro (e.g., local regulation), meso (e.g., State Law), and macro levels (e.g., National Constitutions). Three distinct empirical studies employ a different and unique combination of original legal data and socioeconomic measures. Chapter 1 explores the association between State-Level Family Law in the U.S. and later changes to county-level General Fertility Rates; Chapter 2 interrogates the association between Constitutional Law and later changes to country- level Total Fertility Rates; and Chapter 3 studies the association between grandparents’ visitation rights, and time grandparents spend with grandchildren. A solid foundation of evidence is provided by all three studies to demonstrate that Law is linked to population dynamics, as expected by the theoretical framework introduced, affirming a new role for Law in population dynamics, as set out by the “Law and Demography” agenda.