In this article we address the nexus between Internet and politics looking in particolar at the link between social media and collective action. In making a general plea for abandoning radical approaches that either consider social media as causative of collective action or fear the spread of "slacktivism," we propose to implement current reflections on transformative effects of social media on collective action dynamics with an explicit focus on the networked structures of participation that derive from the use of these communication tools. Thus we propose to consider these structures as an integral part of what we call collective action socio-technical systems, i.e., a multipolar and multidimensional system of technologically enabled social relations that deploys simultaneously online and offline; and to analyze them empirically through a network approach and techniques paying specific attention to actors, connections between them, contents they produce and patterns of contents circulation. We provide here a preliminary application of our framework to the study of a snapshot of online campaigning on Twitter considerino the case of the annual campaign Take Back the Tech! to reclaim media to end gender-based violence.