This article explores a particular pattern of wartime violence, the relative absence of sexual violence on the part of many armed groups. This neglected fact has important policy implications: If some groups do not engage in sexual violence, then rape is not inevitable in war as is sometimes claimed, and there are stronger grounds for holding responsible those groups that do engage in sexual violence. After developing a theoretical framework for understanding the observed variation in wartime sexual violence, the article analyzes the puzzling absence of sexual violence on the part of the secessionist Liberation Tigers of Tamil Eelam of Sri Lanka.