This dissertation explores the strategic formation of counter-hegemonic discourses during social movements and their rescaling through mobile social media across networked, translocal public spheres. Through an interdisciplinary approach drawing on critical discourse analysis, communication studies, and social movement theory, this qualitative research focuses on the discursive constructions of identities and ideologies during the 2009 Iranian presidential election protests. Examining activists' discursive tactics in a corpus of Twitter tweets, Flickr photo uploads, and YouTube videos and comparing them with the interdiscursive strategies of U.S. legacy news media texts, I argue that Iranian activists' use of social media and English add to the micronarratives of vernacular globalization while also calling into question Western master narratives about Iran. I also argue that activists' reflexive discursive practices and symbolic reentextualizations help form transnational sociomental bonds that strengthen collective actors' sense of solidarity, though at the risk of informationalizing their borrowed discourses and constraining their political stance-taking to the level of affect. While the use of new media in recent social movements has attracted scholarly attention in various fields, much of it has been in quantitative and network-mapping studies. This project seeks, therefore, to address the relative lack of qualitative, microlevel perspectives on new media discursive practices in social movements while also engaging arguments on the discursive relationships between cyber-rhetoric and democracy promotion as well as present understandings of how new media discourses shape globalized vernaculars of English.