The National Children's Study (NCS) is planned to be the largest long-term study of environmental and genetic effects on children's health ever conducted in the United States. It proposes to examine the effects of environmental influences on the health and development of approximately 100,000 children across the United States, following them from before birth until age 21. By archiving all of the data collected, the NCS is intended to provide a valuable resource for analyses conducted many years into the future. This book evaluates the research plan for the NCS, by assessing the scientific rig...