This article presents a new approach to the study of public contestation through social media. Developing this approach, we make three conceptual moves. First, to capture the dynamic character of contemporary contestation, we shift attention from publics to publicness as an interactive process. Second, we turn the focus from the “counter,” as a public or space distinct from the dominant sphere, towards distributed forms of contention. Finally, instead of considering media as arenas of claims, we investigate how media are constitutive of contentious publicness, which can be studied along its material, spatial, and temporal dimensions. These moves lead to an analytical framework through which trajectories of contentious publicness can be systematically traced and evaluated. Through case studies on the 2011 Egyptian uprising and the Occupy protests, we demonstrate how this framework can be employed to examine the construction of new contentious actors and evaluate their democratic legitimacy as claim-makers.