As biomedical and behavioral research progresses into new areas, the number of scientists active in various fields rises and falls, and the health needs of the U.S. population evolve, it is important to ensure that the preparation of future investigators reflects these changes. This book addresses these topics by considering questions such as the following: What is the current supply of biomedical and behavioral scientists? How is future demand for scientists likely to be affected by factors such as advances in research, trends in the employment of scientists, future research funding, and changes in health care delivery? What are the best ways to prepare prospective investigators to meet future needs in scientific research? In the course of addressing these questions, this volume examines the number of investigators trained every year, patterns of hiring by universities and industry, and the age of the scientific workforce in different fields, and makes recommendations for the number of scientists that should be trained in the years ahead. This book also considers the diversity of the research workforce and the importance of providing prospective scientists with the skills to successfully collaborate with investigators in related fields, and offers suggestions for how government and universities should structure their research training programs differently in the future.