The Robert Wood Johnson Foundation (RWJF) seeks to build the evidence for and strengthen the use of regulatory, legal and policy solutions to improve public health. RWJF is equally interested in identifying and ameliorating laws and legal practices that unintentionally harm health. As public health practitioners, policy-makers and others consider how laws influence the publics health, they need evidence to inform questions such as: How does law influence health and health behavior? Which laws have the greatest impact? Can current laws be made more effective through better enforcement, or do they require amendment? The purpose of RWJFs Public Health Law Research program is to answer such questions by building a field of research and practice in public health law.