The process of joining an IO may cause liberalization before membership. Thus studies that only evaluate compliance after membership underestimate the effects. Conditional membership may be one of the most important sources of leverage for IOs.  The rule-makers establish rules that don't go far beyond what they would otherwise do, but rule-takers often must accept a broad range of policy reforms they would not otherwise consider. The influence of accession conditions has been studied in the context of EU and NATO, where sizeable benefits and formal conditions motivate major concessions by applicants. This paper proposes to examine a much less powerful organization, the OECD. Here the qualifications for membership are ambiguous and leave open room for informal pressure for a range of economic reforms. The politics of joining organizations touch closely on concerns about status and legitimacy as well as functional demands for cooperation in complex issue areas. I will examine how OECD membership has motivated specific reforms in regulatory policies and trade in a comparison of the East European transition economies accession with that of Japan, Mexico, and Korea. Statistical analysis of patterns of when countries apply for membership will test for the role of economic and political conditions as well as the political relations among members.