Public investment is a shared responsibility across different levels of government – national, regional and local – which makes its governance particularly complex. In today’s tight fiscal environment, making the most of public investment across levels of government is more crucial than ever. National governments have an important role to play in establishing the framework conditions needed to better select and implement sound infrastructure projects. Subnational governments also play a specific role, although this is often neglected in the literature. Subnational governments – defined as all levels of government below the national one, i.e. administrative regions, states/provinces, counties and municipalities – are responsible for a large share of public investment: on average, around 60% in the OECD. Most of this public investment goes to infrastructure.