The “Training and Occupational Skills” (Formation et Qualification Professionnelle: FQP) surveys involve an in-depth examination of respondents’ paths, reconstructing various stages in their life histories. They address a very wide range of questions on society and the economy. Having been conducted six times in forty years, they provide data that shed light on relatively long-term changes. However, the questions asked about society have also changed in the course of such an extended period; so have the issues addressed by researchers. This article discusses a series of five broad aspects of the respondent’s life history: social origins, schooling, continuing education, occupational mobility, and migration history. For each aspect, we mention the main changes in the questionnaire, and seek to move the discussion a step further by shedding light on the reasons for the changes and their context. Our analysis has identified four highly contrasting issues: social inequality, the production system’s skill requirements, human capital, and discrimination. Public-policy concerns differ from one issue to another, but divergences also emerge in the theoretical frameworks, and even in the disciplines applied, as well as in the data-processing methods and—ultimately—in the definition of what constitutes a valid scientific fact.