This article explores the implications of the World Trade Organization's General Agreement on Trade in Services(GATS) for social security. It examines what bearing the GATS has, or will have, on social security policy and administration and what the effects might be. These questions are explored through a review of legal, political and policy issues relating to the status of social security within the GATS and the consequences of applying the Agreement's provisions to social security. The discussion distinguishes between the supply of social security services on the one hand and access to and use of social security services on the other hand. It also distinguishes between substantive questions regarding the scope of the GATS and procedural issues regarding governments' scheduling practices. I argue that although the GATS does not yet have a direct material bearing on social security policy and provision, it may do so in the future. However, it is too early to ascertain what the nature or magnitude of the effects might be. More generally, the discussion highlights the difficulties of securing multilateral cooperation among countries with different levels of "development", strategic interests and priorities, and social security systems. © In ter na tional So cial Se cu rity As so ci a tion, 2005 In ter na tional So cial Se cu rity Re view, Vol. 58, 1/2005 Pub lished by Blackwell Pub lish ing