SUMMARY We are requesting continuation of the NICHD training grant in Demography to the University of Pennsylvania (Penn). The proposed program continues Penn’s longstanding excellence in training in Demography, as per placement of, and scientific contributions by, trainees. It will be enhanced during the upcoming cycle by (a) new engagement of population researchers from the Health Policy Division of the Department of Medical Ethics & Health Policy at the Perelman School of Medicine; (b) a major reorganization of the training sequence in demographic methods; (c) new integrated training in the areas of biomarkers, complex data structures, data science, and quantitative methods; (d) new exchange training programs with two prominent European research centers (Max Planck Institute for Demographic Research and French Institute for Demographic Research); (e) expanded activities to enhance diversity. Six predoctoral positions (no postdoctoral positions) are requested. The principal aim of the Demography predoctoral program at Penn is to train independent researchers who are prepared to play leading roles in population analysis. This goal is achieved through (i) intensive instruction in the methods, theoretical approaches, and empirical substance of demography and allied disciplines; (ii) progressive incorporation of students into faculty research activities; and (iii) subsequent branching into independent research. The training in Demography described in this proposal reflects a vision of the population sciences and population health in which a strong background in the logic of demographic process is the gateway to the application of contributions from elsewhere in the social and behavioral sciences to an array of topics of public and scientific interest.