The overall aim of the proposed project is to increase receipt of a broad array of childhood preventive health services in a population of disadvantaged inner city children. Specific hypotheses concerning risk factors for infant under-immunization and lack of receipt of well child care will be tested. This study will first examine these risk factors in a defined population of inner city children, using a historical cohort. Finally, through the use of a randomized controlled trial in a prospective birth cohort, it will test an intervention, based partly on the evidence gathered from the initial study phases, to increase immunization rates and well child care delivery in those children most at risk for “falling through the cracks.” These studies will be conducted in the Denver Health community health network, the largest integrated community health care system in the United States.