When the World Health Organization (WHO) European Ministerial Conference on Mental Health endorsed the statement “No health without mental health” in 2005, it spoke to the intrinsic — and indispensable — role of mental health care in health care writ large. Yet mental health has long been treated in ways that reflect the opposite of that sentiment. This historical divide — in practice and in policy — between physical health and mental health has in turn perpetuated large gaps in resources across economic, social, and scientific domains. The upshot is a global tragedy: a legacy of the neglect and marginalization of mental health. The scale of the global impact of mental illness is substantial, with mental illness constituting an estimated 7.4% of the world's measurable burden of disease. The lack of access to mental health services of good quality is profound in populations with limited resources, for whom numerous social hazards exacerbate vulnerability to poor health. The human toll of mental disorders is further compounded by collateral adverse effects on health and social well-being, including exposure to stigma and human rights abuses, forestallment of educational and social opportunities, and entry into a pernicious cycle of social disenfranchisement and poverty. Advances in efforts to alleviate the human and social costs of mental disorders have been both too slow and too few.