Systems science: a good investment for the public's health.

This supplement of Health Education & Behavior showcases the current state of the field of systems science applications in health promotion and public health. Behind this work lies a steady stream of public dollars at the federal level. This perspective details nearly a decade of investment by the National Institutes of Health's Office of Behavioral and Social Sciences Research. These investments have included funding opportunity announcements, training programs, developing resources for researchers, cross-disciplinary fertilization, and publication. While much progress has been made, continuing investment is needed in the future to ensure the viability and sustainability of this young but increasingly important field.