This article describes national level development towards a Health in All Policies approach in Finland over the past four decades. In the early 1970s, improving public health became a political priority, and the need to influence key determinants of health through sectors beyond the health sector became evident. The work began with policy on nutrition, smoking and accident prevention. Intersectoral health policy was developed together with the World Health Organization (WHO). When Finland joined the European Union in 1995, some competencies were delegated to the EU which complicated national intersectoral work. The priority in the EU is economy, but the Constitution's requirement to protect health in all policies gives legal backing for including health consideration in the EU-level work. To promote that, Finland adopted 'Health in All Policies' (HiAP) as the health theme for its EU Presidency in 2006. The intersectoral work on health has developed from tackling single health problems, through large-scale programmes, further to systematic work based on legislation and permanent structures. In the 2000s, work at local level was strengthened by introducing more focused and tighter legislation and by providing expert support for implementation. Recently, emphasis has been on broad objectives and Governmental intersectoral programmes, and actors outside the administrative machinery. Great improvements in the population health have been gained over the past few decades. However, health inequalities across social groups have remained unacceptably large. Major decisions on economic policy with varying impacts by the social groups have been made without health impact assessment, or ignoring assessments conducted.