The PSC is anchored by a long, distinguished tradition (J Durand, D Thomas, R Easterlin, E van de Walle, Furstenberg, Preston, J Menken, D Massey, P Morgan, H-P Kohler) in demography. This has expanded in the sustained intersection between the “demographic triad”—fertility, mortality, and migration—and other signature themes (2). These phenomena, plus marriage, divorce, and cohabitation, are the substantive components of the arithmetic of formal demographic methods. A key outcome of their intersection is the age structure. These demographic topics are a major source of intellectual identification across fields within the PSC, as researchers who are not trained in formal demography, but who are studying fertility, marriage, family etc. are attracted to population research (e.g., Fang, Fernández-Villaverde, Greenwood, Lareau, Valeggia). The Graduate Group in Demography (GGD; directed by H-P Kohler, previously by Elo, Watkins, Smith, Zuberi, Preston) is a powerful recruitment and retention tool for PSC faculty with core identities as demographers (e.g., Guillot, Parrado); and a source of skilled research workers for large-scale PSC projects, PSC faculty in departments without access to similarly trained research assistants (e.g., Chang, D Culhane, Katz, MacDonald); and the field more generally (42 current tenured or tenure-track university faculty from GGD graduates 1996-2011).