To some, the G20 offers a representative, legitimate and effective forum for dealing with global economic issues, and represents a distinct improvement on the G8. To others it is seen as still lacking full legitimacy and as being an unlikely institutional vehicle for organising global economic cooperation and coordination. This article assesses these views in the aftermath of the Seoul summit of November 2010. To what extent has the momentum that appeared to have been generated at the London summit in April, 009 been maintained? Many of the more intractable problems facing the world economy were, in fact, deferred in 2009, allowing the impression to be created that there was a higher degree of international consensus than there really was. Moreover, the crisis circumstances at the time placed a high premium on swift policy action. As the crisis has eased, more fundamental disagreements have emerged, and these were reflected by the discussions in Seoul. The reality is likely to be that while it is a useful institution for debate and discussion, and perhaps for helping to resolve disagreement, the achievements of the G20 will probably turn out to be more modest than the London summit might have suggested.