This article discusses the use of the concept of class in health research, different sociological approaches to social stratifi cation and class structure, and the explanatory potential of the class concept in studies on social determinants and health inequalities. It also elaborates on the operationalization models that have been developed for use in sociological, demographic, or health research, as well as the limitations and scope of these models. Four main operationalization models were highlighted: the model developed by Singer for studies on income distribution in Brazil and adapted by Barros for use in epidemiological research, the model of Bronfman and Tuirán to study the Mexican demographics census and adapted by Lombardi for epidemiological research, the model proposed by Goldthorpe for socioeconomic studies in the UK and adapted by the Spanish Society of Epidemiology, and the model proposed by Wright for research in sociology and political science, which has also been used in population surveys in health. In conclusion, each of the models presented is consistent with their underlying theoretical concept, precluding the selection of one model over the others.