The rise of social media has raised questions about the vitality of privacy values and concerns about threats to privacy (Marwick and boyd, 2014). As online communities have flourished, debate over appropriate information flows among users, as well as to platforms, service providers, and surveillance networks, has grown (Ellison et al., 2011;Marwick and boyd, 2014). Facebook has received considerable scholarly attention (e.g. Acquisti and Gross, 2006;Hargittai, 2010) in this debate. Social media use has become pervasive not only in economic and social interactions (Kaplan and Hainlein, 2010) but also in politics and political organizing (Gonzalez-Bailon and Wang, 2016;Nam, 2012). The convergence of politics with social media use amplifies the privacy concerns traditionally associated with political organizing (Breuer, 2016;Nam, 2012), particularly when marginalized groups and minority politics are involved (Stacheli, 1996).Despite the importance of these issues, there has been little empirical exploration of how privacy governs political activism and organizing in online environments. This project explores how privacy concerns shape political organizing on Facebook, through detailed case studies of how groups associated with March for Science, Day Without Immigrants ("DWI"), and Women's March govern information flows. Each of these groups emerged from distributed grassroots efforts, gaining criticalWe thank participants at PLSC, the 2nd Annual CI Symposium, and the Workshop on the Growing Influence of Social Media in Global Politics and Society for their valuable feedback.