Research on the bi-directional relationship between mental health and homelessness is reviewed and extended to consider a broader global perspective, highlighting structural factors that contribute to housing instability and its mental ill health sequelae. Local, national and international initiatives to address housing and mental health include Housing First in Western countries and promising local programmes in India and Africa. Ways that psychiatrists and physicians can be agents of changes range from brief screening for housing stability to structural competence training. Narrow medico-scientific framing of these issues risks losing sight of the foundational importance of housing to mental health and well-being.