What is at stake for how the Internet continues to evolve is the preservation of its integrity as a single network. In practice, however, its governance is neither centralised nor unitary. It is piecemeal and fragmented, with authoritative decision-making coming from different sources simultaneously. To understand how governance emerges and becomes articulated over time in complex issue domains such as the Internet, this thesis sets out a novel, comprehensive framework for theorizing a nascent policy field and for analyzing its evolution empirically. There are three novel aspects of this work: (a) theory-building on the genesis and structuration of governance; (b) unique analysis of over 300 instruments of governance (between 1969 and 2015); (c) first analysis of anchoring practices in Internet governance. This interdisciplinary research adopts a broad perspective that touches on questions of power, rule-creation and praxis of governance. Establishing the case for a wider research agenda on emerging issue areas in International Relations, it responds to calls for understanding dynamic systems of rule as they come into place in contested governance configurations by proposing an empirically-grounded history of Internet governance from the 1970s to date.