Civil society organizations (CSOs) facilitate mobilization for nonviolent protests, yet protests sometimes go on a very violent trajectory, precipitating the onset of civil war. This paper studies the effect of CSOs on protests' escalation to civil war. It argues that while CSOs can facilitate the occurrence of protests, CSOs can have a mediating role in preventing the onset of civil war once protests take place. The facilitating and mediating role of CSOs is conditional on their capacity, which is a function of two dimensions: participation and autonomy from the state. Importantly, CSOs cannot substitute facilitation for mediation before protests occur as the mediating role works only if conflict is not latent. I test the proposition that higher capacity CSOs facilitate the occurrence of protests, but once protests take place, higher capacity CSOs mediate conflict, thereby decreasing the probability of civil war onset as a protests' trajectory. The findings from an empirical investigation with global panel data from 1990 to 2018 show support for this proposition.