This research builds on the social movements theory of networks and coalition building, the theory of digital activism, and the social networks theory of organizations to study the rich case of online mobilization for the 2011 Egyptian revolution. I use the analytical tools of social network analysis to study Twitter networks of activists of the Egyptian revolution in early 2011, when solidarity characterized the movement, and late 2014, when schism spread it apart. In this, I investigate how the repertoire of online activism relates to the on-the-ground movement. The social movements theory of networks states that activists’ ideological congruence, the presence of bridge builders who bring the movement together, and the presence of previous ties among the activists are all factors of coalition building and movement solidarity. This dissertation tested the role of these factors in the Twitter networks of Egyptian activists. The results suggest that digital activism complements rather than mirrors on-the-ground activism. While all three factors influence the network, they manifest somewhat differently than research has suggested they do in offline networks. This dissertation contributes to social movements theory of coalition building through adding validity to its application to digital activism, and suggests modifications to be made while applying this theory to the repertoire of online mobilization. The research has a methodological contribution through using cutting edge techniques of social network analysis to study Twitter networks of activists. Unlike earlier studies on the Egyptian revolution, this methodological approach revealed new findings that could not have been studied through other methods of research. / Dissertation / Doctor of Philosophy (PhD)