This is a summary of the workshop Rebuilding the Unity of Health and the Environment: A New Vision of Environmental Health for the 21st Century. The goal of this workshop was to emphasize the connection between human health and the natural, built, and social environments. This workshop integrated talks from many fields and created a dialogue among various environmental health stakeholders. The language presented in this respect should not be viewed as an endorsement by the Environmental Health Sciences Roundtable or the Institute of Medicine of what action is needed for the future, but rather as an effort to synthesize the various perspectives presented.