The costs of mental ill-health for individuals, employers and society at large are enormous. Mental illness is responsible for a very significant loss of potential labour supply, high rates of unemployment, and a high incidence of sickness absence and reduced productivity at work. In particular, mental illness causes too many young people to leave the labour market, or never really enter it, through early moves onto disability benefit. Despite these very high costs to the individuals and the economy, there is only little awareness about the connection between mental health and work, and the drivers behind the labour market outcomes and the level of inactivity of people with mental ill-health. This series contributes to filling that knowledge gap. It offers both a general overview of the main challenges and barriers to better integrating people with mental illness in the world of work, as well as a close look at the situation in specific OECD countries.