This article examines current appropriations of social media by activists of the radical left in Greece and Sweden. Previous research has shown that the discourse concerning social media’s empowering potential is embedded in commercial values that contradict the value systems of many activists who engage in struggles against the current economic system. We employ the notion of détournement, which describes how social movements turn something aside from its normal course or purpose. Based on interviews and online ethnographic observations, we seek to understand how and with what consequences social media facilitate and limit collective action. The article enhances our understanding of activists’ social media use by turning our attention to the sociotechnical impact of social media on collective action initiated by leftist groups as well as the relationship between ideological loyalties and the political economy of corporate social media.