The transformational potential of using social networking sites (SNS) for activism is a highly researched topic in various academic disciplines, but the topic of ‘success’ has been largely avoided by scholars, much to the detriment of activists themselves, for whom effective use of SNS has become action critical. In this paper, we triangulate findings (incorporating data from surveys, focus groups, and tweets from activists, and combining qualitative and quantitative methods of analysis, chiefly through corpus-based critical discourse analysis) to gain a better understanding of how activists perceive and construct activism on SNS, to describe some features of successful and unsuccessful activist tweets, and to provide some recommendations for heightened impact of activist activities on SNS. To this aim, we describe to what extent certain actions leverage the affordances of digital media and distinguish between categories of action along two dimensions: individualistic vs. collectivistic and persuasive vs. confrontational. We find that activists describe goals that involve individualized, persuasive (and therefore low-risk) activities to be most effectively achieved using Twitter, likely due to fear of police intervention. Activist tweets are found to be retweeted at a dramatically lower rate than a reference corpus of general tweets, and are characterized by lack of original content. We conclude by discussing the various ways in which activists could improve these circumstances and optimize their engagement with SNS by radically increasing their leveraging of the affordances of digital media.