What can further market integration contribute to growth and employment? A series of hypothetical trade reform scenarios explores what countries at different levels of development can expect to gain from reforming tariffs, non-tariff barriers, trade facilitation and domestic support to agriculture. Simulations of multilateral and regional trade agreements with the OECD METRO model show that positive effects are higher when more countries participate in trade integration because it broadens market opportunities, widens the range of products at lower prices, and reduces trade diversion. Smaller economies especially benefit. Firms in these economies can better specialise in international production networks as they have access to larger and more differentiated markets and also benefit from enhanced market access on the products they already produce. While trade integration boosts demand and lifts wages and factor returns, the required production adjustments also leads to reallocation of workers between sectors. The analysis highlights some of the distributional implications and emphasises the need for labour force adjustment policies to accompany trade integration.