For more than 35 years the National Institute of Mental Health (NIMH) has been the nation's major instrument of support for research in mental health. The yield from this ongoing research effort has been substantial, with a substantive increase of information about the causes, treatment, and prevention of mental illness as well as the factors that help foster good mental health. The research has been marked by several trends including: (1) a shift away from oversimplified theories about the development of mental illness; (2) the importance of genetic factors and the effect of drugs on behavior; (3) methodological advances in quantifying observations and judgments of symptoms and behavior; (4) progress in the field of learning behavior; and (5) a focus on the family as a contributor to the development of mental disorders. (Author/HLM)