UNLABELLED: WHY THE COHORT WAS SET UP?: CONSTANCES is a general-purpose cohort with a focus on occupational and environmental factors. COHORT PARTICIPANTS: CONSTANCES was designed as a randomly selected sample of French adults aged 18-69 years at inception; 200 000 participants will be included. DATA COLLECTION PHASES: At enrolment, the participants are invited to complete questionnaires and to attend a health screening centre (HSC) for a health examination. A biobank will be set up. The follow-up includes an yearly self-administered questionnaire, a periodic visit to an HSC and linkage to social and national health administrative databases. MAIN TYPES OF DATA COLLECTED: Data collected for participants include social and demographic characteristics, socioeconomic status, life events and behaviours. Regarding occupational and environmental factors, a wealth of data on organisational, chemical, biological, biomechanical and psychosocial lifelong exposure, as well as residential characteristics, are collected at enrolment and during follow-up. The health data cover a wide spectrum: self-reported health scales, reported prevalent and incident diseases, long-term chronic diseases and hospitalisations, sick-leaves, handicaps, limitations, disabilities and injuries, healthcare usage and services provided, and causes of death. CONTROL OF SELECTION EFFECTS: To take into account non-participation and attrition, a random cohort of non-participants was set up and will be followed through the same national databases as participants. DATA ACCESS: Inclusions begun at the end of 2012 and more than 110 000 participants were already included by September 2016. Several projects on occupational and environmental risks already applied to a public call for nested research projects.