This is an application for a five-year competing renewal of an NICHD Population Research Infrastructure Program at the Population Research Institute (PRI) at The Pennsylvania State University. PRI is a multidisciplinary center that encourages, organizes, and supports research and training in the population sciences. The intellectual environment for population sciences at Penn State is unique among NICHD supported population centers. Research associates in PRI represent 15 departments in 6 colleges. PRI first received NICHD core support for population research in 1991. Since then, and largely as a result of NICHD's infrastructural support, PRI has grown from 27 to 61 associates, has developed a large portfolio of qualifying grants, and has achieved national recognition for its scientific accomplishments. This has contributed to the development of critical masses of faculty within major topical areas of population research and the emergence of unifying crosscutting themes that span these areas. This application requests infrastructural funding to build on these accomplishments while ensuring cost- efficiencies and stability in PRI's research cores (Administrative, Computer, Geographic Information Analysis, Information, and Statistics). Support is also requested for an Infrastructure Development Program to continue PRI's encouragement of interdisciplinary research and innovative methodology. PRI is well positioned in its faculty's research activities, staff expertise, and resources to continue developing as a dynamic and synergistic center for innovative population research.