In case control studies, collection of information on the workplace environment has generally been limited to self-reports of exposures or to job title, type of employer, and the dates the jobs were held, supplemented sometimes by work activities. This information, however, may be insufficient to assess the potential and level of exposure accurately due to recall difficulties and the variability of exposures within a job. A solution to this problem is to use job-specific questionnaires. The organization of a series of such questionnaires developed for a case control study of brain tumors is described. Three types of questionnaires, or modules, were developed, task-based, industry-based, and modules based on jobs with nonspecific types of tasks (e.g., laborer). The format of these modules starts with questions on the general work environment (type of employer) and proceeds to questions on tasks. More detailed information is then gathered on materials and equipment used, sensory descriptions, dermal exposure, work practices, engineering controls, and personal protective equipment use. The questionnaires cover a wide variety of exposures including solvents, heavy metals, polycyclic aromatic hydrocarbons, machining fluids, electromagnetic frequency fields, and many other exposures and, therefore, can be used in other case control studies.