Increasing demands on ecosystems, decreasing biodiversity, and climate change are among the most pressing environmental issues of our time. As changing weather conditions are leading to increased vector-borne diseases and heat- and flood-related deaths, it is entering collective consciousness: environmental issues are human health issues. In public health, the field addressing these issues is known as environmental health. This field addresses both the effects people have on their environment as well as the effects of the environment on people. Psychology, as a discipline concerned with explaining, predicting, and changing behavior has much to contribute to these issues because human behavior is key in promoting environmental health. To date, however, an integrative view of environmental health in psychology is lacking, hampering urgently needed progress. In this paper, we review how the environment and human health are intertwined, and that much can be gained through a systemic view of environmental health in psychology. Based on a review of the literature, we suggest that psychologists unite efforts to promote an integrative science and practice of environmental health psychology, and jointly address environmental-health related behavior. The research agenda for this field will include integrating behavior change theory and intervention approaches. Thereby, psychology can potentially make an important contribution to sustained environmental health for generations to come.