PROJECT SUMMARY/ABSTRACT The central objective of this training grant is to prepare young scientists to make enduring contributions to child digestive health, a goal that has disproportionate importance in the survival, growth, and well-being of our populations. This program will achieve this goal by providing immersive research training at Washington University School of Medicine in fields relevant to digestive health challenges of children worldwide. The rationale for our training program is based on two premises. First, high quality research training is critical for successful academic careers. Second, few individuals are being trained to solve problems relevant to the childhood digestive system. The program spans diverse disciplines, but all mentors and their projects have in common a dedication to research relevant to the digestive health of children, strong mentorship records, and commitment to integrate trainees into existing projects and offer individualized preparation for research careers. This application represents an evolution of this successful training program by expanding support to pre-doctoral students, and by proposing an increasingly visible and formal role in the Washington University School of Medicine's Division of Biology and Biological Sciences. The program uses a three track system: In Track I (Microbial ? Host interactions in the Gastrointestinal Tract), trainees determine how microbes (specific pathogens or microbial populations) affect childhood digestive health. In Track II (Cellular and Molecular Biology of the Developing Gastrointestinal Tract), trainees dissect molecular and genetic aspects of congenital and acquired disorders of the childhood gastrointestinal system. In Track III (Translational Biology of the Gastrointestinal Tract), trainees use data primarily from humans to find causes, treatments, and prevention of digestive disorders of childhood. This training program will fund four post-doctoral trainees (who have MD, PhD, or MD-PhD degrees), and two pre-doctoral degree candidates. We will draw from our traditional base of pediatric gastroenterology fellows and qualified post-doctoral associates, strengthened in the past five years by extension to surgical residents. We will also offer training opportunities to pre-doctoral students, by providing entry into a program that also include a new course childhood digestive pathobiology. This program will remain integrated into the Washington University Digestive Diseases Research Core Center. The amalgamation of trainee pipeline and opportunities under the umbrella of this training grant will strengthen our growing and multi-level collaborations between pediatric gastroenterology and surgical research in our institution. We will build an inclusive, but identifiable, community of trainees and mentors. The goal is to produce scientists with enduring interests in childhood digestive diseases and the causes, treatments, and prevention of these illnesses.