The prognosis for children with cancer has improved dramatically over the past decades with an overall 5-year survival rate now at 84%. However, the late effects of cancer treatment, including permanent organ and tissue damage, hormonal and reproductive dysfunction and second cancers, are of special concern, with more than 40% of the estimated 360,000 survivors of childhood cancer experiencing a significant health-related quality of life complication from childhood cancer and its treatment. In addition, progress for a number of childhood cancers remains limited with approximately 50% of children with acute myelogenous leukemia, 50% of children with high-risk neuroblastoma, and more than 90% of children with brainstem glioma, still succumbing to their disease. The Children’s Oncology Group (COG), the world’s largest organization devoted exclusively to childhood and adolescent cancer research, and its multidisciplinary research teams comprised of more than 9,000 members, conducts research at more than 220 leading children’s hospitals, universities, and cancer centers. This proposal is for the COG NCI Community Oncology Research Program (NCORP) Research Base to continue its collaborative research work for our 26 community and 16 minority/underserved NCORP sites. With COG’s significant scientific, statistical, data management and information technology infrastructure, we seek to conduct pediatric clinical trials to define optimal treatments, and conduct laboratory research that will translate into more effective treatments with reduced side effects. The COG directly addresses the NCORP goals of providing access to state-of-the-art cancer treatment at community sites while conducting research in cancer control, including post-treatment surveillance/survivorship, and cancer care delivery. We promote the participation of community-based investigators in all of COG’s research, governance and administration and in NCORP Network activities. The COG’s research goals are to reduce overall mortality and morbidity, decrease acute and delayed treatment-related toxicities, and develop more effective ways of delivering care to children, adolescents and young adults. The COG NCORP Research Base is uniquely positioned to elucidate the impact of different health care delivery characteristics on outcomes, to identify determinants of poorer outcomes in underserved groups including adolescents and young adults, and to develop targeted strategies aimed at eliminating disparities and improving efficiencies for the delivery of cancer care in young persons with cancer.