During civil conflicts the distribution of power heavily influences belligerents’ war strategies, potentially including civilian targeting. Despite the potential relevance to wartime victimization, the relationship between insurgent capabilities and civilian victimization has received limited attention. A complicating factor in assessing this relationship is that power produces countervailing incentives and opportunities for violence. While greater military capabilities present more opportunities for death and destruction, incentives for anti-civilian violence should decline as the range of war strategies available to the group expands. This intuition suggests a tension between the opportunities and incentives to kill that past studies have failed to explicitly address. I help resolve this tension by examining the manner in which the origins of rebel resources condition the relationship between military capabilities and civilian victimization. Where groups rely on local support, violence declines as group capabilities increase. By contrast, when rebels rely on alternative sources of support, greater capabilities produce greater levels of violence. I test these relationships quantitatively using recently constructed data on insurgent resources and one-sided violence against civilians in conflicts occurring between 1989 and 2009.