Green growth means achieving economic growth while reducing pollution and greenhouse gas emissions, minimising waste and improving efficiency in the use of natural resources. This requires long-term investment and sustained financing. Public budgets have traditionally been an important source of green infrastructure financing. But given the strains on public finances, large-scale private investment will be needed for the transition towards a green economy. Governments have a key role to play in strengthening domestic policy frameworks to catalyse and mobilise private finance and investment in support of green growth. It is necessary to better align and reform policies across the regulatory spectrum to overcome barriers to green investment, and to provide an enabling environment that can attract both domestic and international investment. This OECD series on Green Finance and Investment provides policy analysis and guidance to scale up financing and investment in technologies, infrastructure and companies that will be critical in the transition to a low-carbon, climate-resilient and resource-efficient economy.