A growing literature links experiences of armed conflict with postwar political behavior. This paper examines how legacies of wartime violence shape dynamics of protest in twenty-first-century Iraq. We argue that experiences of shared violence against civilians generate strong social and organizational ties, as individuals turn to neighbors, friends, and communal organizations or social groups to help them cope. These strengthened social networks endure beyond the end of the conflict, forming important vehicles that can facilitate the organization of protest when new grievances or opportunities arise. Further, we posit that these effects will be strongest when the perpetrator of wartime violence is a clear out-group—e.g., a foreign army or non-coethnic militia—which facilitates network strengthening by creating a sense of collective victimization and in-group solidarity. We support these arguments using an original database of Iraqi protests from 2010 to 2012 and data on civilian casualties during Iraq’s 2004–2009 conflict. We further test our argument with geo-referenced Arab Barometer surveys. We leverage a case study of Fallujah, based on original interviews and other qualitative data, to unpack mechanisms of network strengthening, endurance, and reactivation during the Iraqi protest wave of 2011.