Citizen expectations about health services are growing, populations are ageing and health care needs are becoming more complex and costly. In this context, primary health care systems are being asked to do more and do things differently. As the first point of contact, strong primary care that provides comprehensive, continuous, and co-ordinated health care is key. It has the potential to improve health system efficiency and health outcomes for people across socio-economic levels, and make health systems people-centred. This report examines primary health care systems across OECD countries, and shows it is still not living up to these expectations in many countries. Doing things differently in primary health care – through new models of organising services, better co-ordination among providers, better use of digital technology, and better use of resources and incentives – helps to improve care, reduce cost growth, and reduce health inequalities. This report identifies key policy challenges that OECD countries need to address to realise the full potential of primary health care, and reviews their main progresses and innovations in their journey towards transforming primary health care for the 21st century.