Abstract
This paper describes how the number of people suffering from mental ill-health has been under-estimated in urban areas in Africa, Asia and Latin America. It also explains how the complex range of factors that contribute to mental ill-health, and the ways in which they interact, remain poorly understood. It then describes the findings from research on mental health in three sub-districts of São Paulo City: one with relatively poor quality housing and low-income households, one predominantly middle-class with better housing and one with high-class housing and high average incomes.