Nearly ten years after its inception, the Internet Governance Forum (IGF) has become an integral, although somewhat fragile, part of the regulatory landscape of the Internet. This paper sets out to analyze the emergence and development of the IGF as the outcome of simultaneous processes of institutionalization and de-institutionalization. For nearly two decades, the predominant belief in Internet governance has been that the Internet should not be managed by an intergovernmental body such as the International Telecommunication Union. While a majority of actors are united in their opposition to a multilateral regime, there is no consensual blueprint for an alternative model. As a result, Internet governance has become an experimental and contested site for exploring non-governmental modes of legitimate oversight and accountable rule-making. The IGF, a hybrid of a UN-based and a multi-stakeholder organization, epitomizes this struggle over institutionalizing and de-institutionalizing a governance regime.