In recent years mobile phones and the internet have played an increasingly significant role, assisting in the organization of dissent worldwide. Only a few studies have dealt with the interplay between social movements and these digital media in Latin America so far. The aim of this PhD thesis is to investigate the empowering potential of internet and mobile phones with regard to mobilization as well as the organization and the dissemination of collective action in an environmental movement opposing the construction of pulp mills and the forest exploitation model in Argentina and Uruguay from 2005 to 2008, a period that coincides with the beginning of the popularization of these digital technologies in these countries. The study relies on interviews with key activists, website analysis of homepages and interviews with key journalists. Drawing on theories on civic engagement and ICTs, social movements media, social movements and collective action as well as public sphere, this thesis reveals that internet and mobile phones supported mobilization and the organization and communication of collective action. Even though the internet and mobile phones functioned as a means facilitating the interplay between key activists and journalists, the dominating event-centered journalistic logic was not challenged. Personalized forms of action and new ways of engaging in action from the private towards the public were beginning to be negotiated among these activists.