This book assesses the nation’s future needs for biomedical and behavioral scientists and the role the National Research Service Awards (NRSA) program can play in meeting those needs. The year 1994 marks the twentieth anniversary of the National Research Act of 1974 (PL 93-348), which established the NRSA program. In its twenty years of operation, the NRSA program has made it possible for many thousands of talented individuals in the basic biomedical, behavioral, and clinical sciences to sharpen their research skills and to apply those skills to topics of special concern to the nation, such as aging, hypertension, the genetic basis of disease, acquired immune deficiency syndrome (AIDS), cancer, environmental toxicology, nutrition and health, and substance abuse.