PIP: This paper presents the research methodology that applied existing data to the study of environmental and health inequalities in Accra, Ghana, and Sao Paulo, Brazil. After an introductory section, the paper considers why more research in this area is necessary and the reasons why information on cities in the South is lacking. The third section describes the aims and methods of the study by 1) looking at the development of the methodology, a form of descriptive epidemiology that uses existing data on morbidity and mortality rates to explore and describe the intra-urban distribution of health and environmental conditions in each location; 2) discussing the creation of an index of socioenvironmental deprivation based on judgements about the validity and quality of data on various socioeconomic and environmental indicators made by working groups in each location; and 3) reviewing data collection techniques and problems with data quality. Section 4 summarizes the results of the study by first noting that the study proved that existing data can be used to identify the extent of intra-urban differentials in environmental and health conditions and then presenting the results of the data analysis that exposed the myth of urban benefits by revealing the unequal distribution of socioeconomic conditions and exposed the myth of urban health by revealing the inequalities in life chances between groups in each setting. The concluding section explores the relevance of these results in environmental and health terms. A main achievement of the study was to introduce a method that allowed planners and policy-makers to work together to devise complex definitions of deprivation using existing data and to use the resulting information for actual decision-making to reduce inequalities.