Existing research on terrorism as a strategy has largely neglected the apparent differences in what groups target. Whereas some organizations primarily target undefended civilians, other attack mainly official and hard targets. I develop an explanation of terrorist groups' relative target preferences based on how a group's ties to its constituency and specific government repressive strategies either constrain or incentivize terrorist attacks against soft civilian vs. hard/official targets. Specific sources of support and the degree of out-group antagonism in their constituency shape terrorist groups' primary targeting strategy. While groups with transnational support are generally more likely to target primarily undefended civilians, not all groups with local support are restrained. Groups with low out-group antagonism and local civilian support incur high political costs for targeting civilians and focus primarily on official targets. Instead, groups with domestic support but high out-group antagonism have mixed incentives. When facing indiscriminate government repression these groups become more likely to target primarily undefended civilians, because they can justify such a response to their audience, direct attacks against out-group civilians, and radicalize local constituents. Indiscriminate repression, however, does not change the targeting strategy of groups who face high political costs for attacking civilians. I examine the observable implications of the theory in a comparative analysis of terrorist organizations (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) as well as an over-time analysis of repression and targeting in the Israeli-Palestinian conflict (1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004), and find strong support for the theoretical argument.What explains these differences in terrorist targeting strategies? And when are undefended civilians more likely to be targeted in terror attacks? The primary purpose of this article is to answer these related questions from an actor-level perspective.Extant terrorism research has mainly focused on structural causes and determinants of attack frequency and lethality. While providing substantial insights, this approach cannot explain who is targeted in terrorist attacks and why. These are important questions because they tell us when specific targets are most at risk, and thus improve counterterrorism efforts, as well as mitigate the human costs of terrorism. 2 Of course, conflict scholarship has analyzed attacks against civilians, but it has typically looked at civilian targets in isolation, without considering the choice of such targets in the context of other available options (e.g., public officials, police, and low-casualty targets such as property). 3 This exclusive focus on soft civilian targets has several shortcomings. First, it has little to say about more discriminate terrorist strategies such as those of the NPA or FSA, and whether different targets ar...