• Tariffs still matter. • Full tariff liberalisation to 2010 would generate dynamic welfare gains of $1 200 billion (at 1995 prices), equivalent to 3 per cent of World GDP in 2010, from greater efficiency and higher productivity. • Developing countries stand to gain relatively more from multilateral tariff liberalisation, with aggregate gains amounting to nearly 5 per cent of their GDP in 2010. • The next WTO round will provide an opportunity for members to improve their living standards. Realising this potential, however, poses a major policy challenge to developing countries.