Does the Internet change the balance of power between authoritarian regimes and their domestic opponents? The results of this case study of Egyptian digital activism suggest that the Internet has important effects on authoritarian politics, though not necessarily the kind we have come to expect from popular accounts of online activism. In this dissertation, I argue that what I call Social Media Networks can trigger informational cascades through their interaction effects with independent media outlets and on-the-ground organizers. They do so primarily through the reduction of certain costs of collective action, the transmission capabilities of certain elite nodes in social and online networks, and through changing the diffusion dynamics of information across social networks. An important secondary argument is that while states, including Egypt, have become more adept at surveillance and filtering of online activities, SMNs make it impossible for authoritarian countries to control their media environments in the way that such regimes have typically done so in the past. Case studies of media events in Egypt between 2006 and 2008 explain how SMNs undermine the process of authoritarian media control and why the independent press is critical for claims-making and the building of shared meaning. However, the power of SMNs is not capable of challenging the entrenched repressive capacity of determined states, nor can SMNs be substituted for the difficult work of grassroots organizing. I arrive at this conclusion through a case study of the April 6th Youth Movement, which staged nearly identical strikes on April 6th, 2008, and April 6th, 2009, with divergent results. Therefore, the dissertation concludes that even though SMNs may lead to richer information environments with increased capacity for organizing, the technologies themselves are not determinative of political outcomes. Finally, by studying the use of digital tools by Muslim Brothers and Baha’is, the dissertation argues that SMNs can provide critical public space and create discursive focal points for political and religious minorities.