In recent years open data initiatives, which make government data publicly available in a machine-readable format for reuse and redistribution, have proliferated, driven by the launch of open-data government initiatives such as data.gov and data.gov.uk. Research on open data has focused on its potential for governance, its implications on transparency, accountability, and service delivery, and its limitations and barriers of use. However, less attention has been focused on the practices of data intermediaries-an emerging configuration of actors that plays an essential role in facilitating the use and reuse of data by aggregating open government data and enhancing it through a range of data practices. This thesis will assess the data practices of open government data intermediaries from three perspectives. First, it will trace the development of open government data initiatives to contend that at a moment when open data policy is seeing global diffusion with the potential of increasing social, political, and economic impact, there is a crucial need to assess the practices of intermediaries to understand how open government data is put to use. Second, it will develop a framework to analyze the role of open government data intermediaries by proposing a definition for "the data intermediary function" constituted by a range of technical, civic, representational, and critical data practices. Third, it will assess the data practices of two open government data intermediaries, 596 Acres and Transparent Chennai, who as urban actors facilitate the conversion of open government data into actionable information for communities to effect changes in the built environment. In describing and assessing the tools, practices, and methods developed by open data intermediaries this thesis will explore the potential and limitations of data intermediaries, and offer recommendations that might inform future open government data initiatives that seek to mediate open government data to facilitate changes in the built environment.