Today [October 24], we publish the Lancet Public Health Commission on gambling—an inquiry and response to a neglected, understudied, and expanding public health threat. Gambling is not a simple leisure activity; it is a health-harming addictive behavior. The harms associated with gambling are wide-ranging, not only affecting an individual’s health and wellbeing, but also their wealth and relationships, affecting families and communities with potential lifelong consequences, and deepening health and societal inequalities. By assessing the barriers to preventing gambling-related health harms, the Commission unveils and deciphers the intersections between the social, commercial, legal, and political determinants of health.