Assessing occupational exposures and their trends over time is a critical component of any public health system for monitoring occupational risks. It involves examining not the occurrence of diseases, but the frequency and distribution of exposures to potentially pathogenic factors among the workforce. This article aims to provide a brief description of the main methods for assessing occupational exposures among all workers in France, from a population-based perspective. It describes the wide variety of tools available and demonstrates how the regular collection of structured information enables the production of various indicators useful for guiding and prioritizing prevention efforts. Thus, to address occupational exposure, the following will be described in turn: questionnaire surveys—particularly through tests and scores—to assess specific exposures; then cohorts, databases of ambient measurements, biometrology, job-exposure matrices, culture-exposure matrices; and finally, exposure modeling. By definition, occupational exposure to chemical, physical, or biological hazards, or to organizational stressors, occurs prior to the onset of any work-related illness. Addressing this determinant is a key lever for preventing illness and preserving workers’ health, regardless of their occupation.