Civil resistance is a powerful strategy for promoting major social and political change, yet no study has systematically evaluated the effects of simultaneous armed resistance on the success rates of unarmed resistance campaigns. Using the Nonviolent and Violent Conflict Outcomes (NAVCO 1.1) data set, which includes aggregate data on 106 primarily nonviolent resistance campaigns from 1900 to 2006 with maximalist political objectives, we find that contemporaneous armed struggles do not have positive effects on the outcome of nonviolent campaigns. We do find evidence for an indirect negative effect, in that contemporaneous armed struggles are negatively associated with popular participation and are, consequently, correlated with reduced chances of success for otherwise-unarmed campaigns. Two paired comparisons suggest that negative violent flank effects operated strongly in two unsuccessful cases (the 8-8-88 challenge in Burma in 1988 and the South African antiapartheid challenge from 1952 to 1961, with violent flanks having both positive and negative impacts in the challenge to authoritarian rule in the Philippines (1983–1986) and the South African antiapartheid campaign (1983–1994). Our results suggest that the political effects are beneficial only in the short term, with much more unpredictable and varied long-term outcomes. Alternately, violent flanks may have both positive and negative political impacts, which make the overall effect of violent flanks difficult to determine. We conclude that large-scale maximalist nonviolent campaigns often succeed despite intra- or extramovement violent flanks, but seldom because of them.