Most drugs prescribed for children have not undergone age-specific studies of pharmacology, safety or efficacy. To address this problem, the FDA now requires industry to provide data for pediatric age-specific labeling for some marketed drugs and for many new molecular entities. A major barrier to conducting these trials is a lack of institutions and programs capable of performing them. To develop such facilities and conduct high priority trials, NICHD created the PPRU Network. The Children's Hospital of Philadelphia (CHOP) proposes to join this Network and will bring to it a large, diverse population of pediatric patients, a strong record of performance and publishing in clinical trials, the powerful pharmacology and biostatistical resources of the University of Pennsylvania School of Medicine (PENN), and the capabilities of a contract research organization through CHOP's alliance with the Duke Clinical Research Institute. Aim 1 creates a locus for studies of pharmacology, safety and efficacy of new and available drugs. CHOP's PPRU studies will utilize the General Clinical Research Center. The Pharmacology Core Laboratory is located in close proximity to the Center for Outcomes Research and the Division of Biostatistics. CHOP will use standard operating procedures, systems of internal and external auditing and monitoring and formal training of investigators at all levels to provide quality assurance for protocol performance and data. An Advisory Board will oversee PPRU activities. CHOP proposes to use literature review and metananlyses, and, most importantly, to conduct appropriate clinical trials to gather information about and promote age-specific labeling of drugs ( Aim 2). In addition to studies of conventional drugs, the institution is heavily committed to gene therapy and other molecular approaches to disease and to the development of new delivery systems, formulations, and surrogate markers to promote their use (Aim 3). Aim 4 addresses the issue of genetic polymorphisms and modeling. The Pharmacology Core Laboratory has expertise in analyzing CYP polymorphisms and has a strategic plan for determining important racial and genetic polymorphisms in children. Training of clinical investigators and pharmacologists will take place in the context of standard operating procedures for each trial ( Aim 5). Continued medical education will be provided by the Center for Epidemiology and Biostatistics (CCEB) and masters and PhD level degrees in Clinical Pharmacology will be encouraged. The institution is providing stipends for medical students to nurture interest in clinical pharmacology. CHOP and PENN have gathered a formidable array of resources to create an imaginative, productive and successful PPRU program.