We develop a model explaining how criminal organizations strategically use pre-electoral violence as a way of influencing electoral results and politicians' behaviour.We then characterize the incentives to use such violence under different levels of electoral competition and different electoral rules.Our theory is consistent with the empirical evidence within Sicily and across Italian regions.Specifically, the presence of organized crime is associated with abnormal spikes in violence against politicians before elections-particularly when the electoral outcome is more uncertain-which in turn reduces voting for parties opposed by criminal organizations.Using a very large data set of parliamentary debates, we also show that violence by the Sicilian Mafia reduces anti-Mafia efforts by members of parliament appointed in Sicily, particularly from the parties that traditionally oppose the Mafia.