Why and how do information and communication technologies (ICTs) shape the intensity of rebel violence? Recent studies find that ICTs can both increase and decrease such violence. We argue that, during civil wars, this effect depends on the type of ICTs. Mobile phones give rebels better military coordination to organize violence. In contrast, the internet increases the constraints of rebel groups to use violence. On the one hand, the internet increases the visibility of rebel groups forcing them to moderate their levels of violence. On the other hand, the internet gives rebels’ opponents better tools to limit the levels of rebel violence. We test these two arguments empirically with panel data of rebel violence in countries experiencing a civil war from 1989 to 2007. Through a series of negative binomial regressions, we find general support for our hypotheses. For the case of the internet, we specifically find that its effects are concentrated in more recent periods when social media became more widespread.