Since the mid 1980s a substantial amount of research has been undertaken on trade in services. Much of this is inspired by the WTO or regional trade agreements, especially the EU, but an increasing number of papers focus on the impacts of services sector liberalization. This paper surveys the literature, focusing on contributions that investigate the determinants of international trade and investment in services, the potential gains from greater trade (and liberalization) and efforts to cooperate to achieve such liberalization through trade agreements. There is increasing evidence that services liberalization is a major potential source of welfare gain, and that the performance of service sectors, and thus services policies, may be an important determinant of trade volumes, the distributional effects of trade, and economy-wide growth. Relatively little research has been done on the political economy of services trade and investment policies and the implications for the design of international cooperation -whether trade agreements or development assistance. This is an important lacuna given the extensive efforts that are invested by governments in the pursuit of such cooperation, both bilateral and multilateral.