This report sets out the range of the OECD’s work with developing countries in 2019. The OECD’s work has evolved from modest efforts in the 1990’s to reflect the global nature of the tax policy and administration issues that come with a globalised economy. Today, the OECD provides a wide variety of assistance to developing countries to ensure that they benefit from advances in tax co-operation and transparency. While supporting developing countries in the fight against tax evasion and avoidance has been the main priority in its capacity building work, in 2019, the OECD extended its reach to include the full range of its tax policy and administration work as part of its development agenda. This provides developing countries with worldclass expertise on tax, high quality internationally comparable data, tailor-made guidance and tools, and direct capacity building support.