The aim of this review was to provide an evidence base for policy development on vocational rehabilitation - defined as whatever helps someone with a health problem to stay at, return to and remain at work. The focus was on adults of working age, the common health problems that account for two-thirds of long-term sickness (mild/moderate musculoskeletal, mental health and cardio-respiratory conditions) and work outcomes (staying at, returning to and remaining in work). Data from some 450 scientific reviews and reports were included in evidence tables. The review demonstrates that there is a strong scientific evidence base for many aspects of vocational rehabilitation, a good business case for it and more evidence on cost-benefits than for many health and social policy areas. Generic and condition-specific findings are reported, and practical suggestions offered for the differing types of people affected by health problems. Vocational rehabilitation should be a fundamental element of government strategy to improve the health of working age people.