The present paper reports on a study, which investigated explanations of health and illness among adolescents from three socio-economic backgrounds in Sao Paulo, Brazil. Interviews and group discussions were used to elicit definitions of health and illness, explanations of illness causality and prevention and maintenance of health among 31 deprived adolescents with recent experience of living on the streets, 20 adolescents from poor families and 20 adolescents from privileged families. The findings showed that adolescents from different socio-economic conditions draw upon similar explanatory models to make sense of health and illness. There were also clear distinctions between the groups. Health and illness were presented as being dependent upon multiple factors such as resistance of the body and socio-economic status among privileged adolescents. In contrast, the explanations offered by deprived and poor adolescents for both health and illness rested on behaviour or exposure to environmental hazards. Moreover, drugs, sexually transmitted diseases and faith in God were prominent features of the accounts from deprived adolescents. The findings suggest a need for health professionals to be sensitive to people's perspectives of health and illness and their link to socio-economic conditions. To emphasize individuals' behaviour in the provision of health-related information among deprived adolescents might be counter productive and reinforce victim blaming.