This thesis will explore contentious politics in China and the role of digitally mediated social networks as mobilizing structures for contentious collective action. Drawing on a case study of a group of sixteen high school students in Beijing, this research analyzes their use of Weixin, a multi-functional instant messaging platform, to develop and maintain their social networks, and how the changes to their networks of strong and weak ties may be conducive to mobilization of contention. This study also explores the potential for this communication platform to become a robust counterpublic sphere in which its 355 million users can feel free to express themselves. The findings of this research demonstrate that most users believe Weixin to be a private communication space, populated by trusted ties, with whom they feel free to express themselves. However, suspicions of state surveillance and incidents of censorship have had an impact for wary users. While networks mediated by Weixin are primarily virtual extension of real intermittent networks, users have found this platform to have an impact on increasing their strong ties, and building trust in their relationships. In times of crisis, and in the final decision-shaping process of mobilization, it is these strong ties that make networks so valuable. However, the respondents do not show a great propensity to use Weixin to build a more heterogeneous network that affords them access to a broader range of social groups and information, a necessary precondition for the socialization function of networks in mobilizing contentious collective action. / Graduate / 0615 / cindytse40@hotmail.com