The authors respond to an article published in a special issue on youth sexuality (Issue No. 323 of *La Santé de l'Homme*), offering a critique of the research conducted with this population group. They outline their perspective, as researchers, on epidemiology as applied in sociological or psychosociological contexts, with its three levels (descriptive, analytical, and evaluative). They, in turn, offer a critical analysis of the concepts presented in the article, drawing on a survey they conducted in Switzerland among adolescents aged 15–20. They then discuss survey methods, the development and implementation of which involve a number of prerequisites regarding the populations studied, the multidisciplinary nature of the professionals involved, and the ethical standards to be observed. They also discuss the researcher’s approach and responsibility in reflecting on the effects of disseminating the results obtained, offering proposals that address the questions and needs identified, with a view to informing health policy.