This research addresses the emergence of emancipatory practices in the field of communication, as part of the growing mobilisations on media and communication issues. By emancipatory communication practices (ECP) I mean ways of social organising that seek to create alternatives to existing media and communication infrastructures. Examples of emancipatory communication practices include independent information platforms, ‘alternative’ radio and video productions, and the operation of communication infrastructures such as not-for-profit Internet Service Providers. By becoming involved in these activities, activists aim at bypassing the politics of enclosure and control enacted by states and business groups. They seek to empower groups and individuals to communicate on their own terms. The study focuses on two types of ECP that have emerged around an ‘old’ and a ‘new’ medium, namely community radio and radical internet projects. I analyse these projects as instances of organised collective action, and look at them through the lens of social movement research. In particular, I adopt an interactionist perspective (Melucci 1996), focusing on sense-making processes. I analyse movement formation and identity processes in order to understand how people mobilise on technological ‘expert’ issues. I investigate organisational structures to comprehend how organisations reflect the way collective identities are built around technology. I also look at action repertoires in interaction with perceived political opportunities. Not only do ECP activists mobilise ‘inside’ and ‘outside’ institutions, they also mobilise ‘beyond’ (i.e. supposedly independently of) the political process. Finally, I explore the networking strategies of ECP actors, and identify the respective ‘movement dynamics’. I analyse whether the collective action observed is a transnational social movement in the making. I argue that collective action on media and communication issues (that includes ECP, but also other groups) can be considered a ‘karst movement’. Like a karst river, such movement remains underground, surfacing only when the environmental conditions are favourable (e.g. where a policy window opens or following an episode of repression).