This paper describes the findings of an eight-year study on human health and community engagement in Anjukudisai, an "objectionable" slum in Chennai. It shows that human behaviour, constrained by socio-economic factors, often leads to ecosystem degradation and frequently causes reactions that jeopardize people's health. Furthermore, insitutional structures often prevent holistic integrated thinking and action. Urban health issues are closely linked to both environmental and socio-economic conditions. The impact of environmental degradation is often most severe on the poorest segments of society: slum dewllers, women, children, and the elderly.