Recent protest movements such as Occupy Wall Street in the US, the indignados/15M movement in Spain, and UK Uncut have witnessed the rise of social media teams, small activist groups responsible for managing high-visibility and collective activist social media accounts. Going against dominant assertions about the leaderless character of contemporary digital movements, the article conceptualises social media teams as ‘digital vanguards’, collective and informal leadership structures that perform a role of direction of collective action through the use of digital communication. Various aspects of the internal functioning of vanguards are discussed: (a) their formation and composition; (b) processes of internal coordination; (c) struggles over the control of social media accounts. The article reveals the profound contradiction between the leadership role exercised by social media teams and the adherence of digital activists to techno-libertarian values of openness, horizontality, and leaderlessness. The espousal of these principles has run against the persistence of power and leadership dynamics leading to bitter conflicts within these teams that have hastened the decline of the movements they served. These problems call for a new conceptual framework to better render the nature of leadership in digital movements and for new political practices to better regulate the management of social media assets.