Social inequalities in health have long been demonstrated, but the understanding of these inequalities remains unclear. Work and its related occupational factors may contribute to these inequalities. The objective of this study was to study the contribution of work factors using an integrated approach (including all types of exposures) to social inequalities in three health outcomes: poor self-reported health, long sickness absence, and work injury. Respondents were 14,241 men and 10,245 women drawn from a survey of the national French working population (response rate: 96.5%). Work factors included job characteristics, and occupational exposures of the physical, ergonomic, biological, chemical, and psychosocial work environment. All work factors were measured through expert evaluation by occupational physicians, except psychosocial work factors, which were self-reported. Strong social gradients were found for all work factors, except for psychological demands, workplace bullying, and aggression from the public. Marked social gradients were also observed for the health outcomes studied, blue collar workers being more likely to report poor self-reported health, long sickness absence, and work injury. The social differences in health were reduced strongly after adjustment for work factors (psychological demands excluded) by 24-58% according to sex and health outcomes. The strongest impacts were found for decision latitude, ergonomic, physical, and chemical exposures, as well as for work schedules. A detailed analysis allowed us to identify more precisely the contributing occupational factors. It suggests that concerted prevention of occupational risk factors would be useful not only to improve health at work, but also to reduce social inequalities in health.