Part-time work is becoming more important in OECD countries, particularly as some groups with traditionally low labour force participation – such as mothers, youth and older workers – take up work in greater numbers. Despite recent regulatory changes to improve the quality of part-time jobs, workers holding these jobs still face a penalty compared with full-time workers in terms of pay, job security, training and promotion, have higher risk of poverty and are less likely to have access to unemployment benefits or re-employment assistance if they become unemployed. However, in terms of job satisfaction, these disadvantages appear to be offset by more family-friendly working-time arrangements and better health and safety. Overall, part-time work promotes higher labour force participation and can be a viable alternative to inactivity for many, if appropriate incentives are in place. In countries with a high share of part-time employment, few part-timers move into full-time work and many stay in part-time jobs for long periods. This may be by choice, but can also have adverse long-term impacts for individuals, and for aggregate labour supply in ageing OECD societies. It is important to remove barriers to moving into full-time work. Notably, tax and benefit systems often reduce the gain from working more hours and can hinder transitions between parttime and full-time work.