This paper draws on Charles Tilly's (2003) development of the concept of collective violence, which he views as a strategy for obtaining group goals rather than part of a creed or ideology. Under this concept, the current paper argues that a terrorist group should be viewed as part of a larger field of actors involved in a social movement. The terrorist group is the agent of CA on behalf of the movement. The CA as a political phenomenon involves the agent of CA (a social movement) that engages in aggressive politics as the means of CA, which is targeted against authorities (the target of CA) and embedded within a structure of conflict (context of CA). The shift toward political terrorism by one actor (the Tanzim in the case study) within the larger movement is usually the result of how the various components of the conflict interact and mutually affect one another. As this paper shows in the case study of the Tanzim in its conflict with Israel, the shift to terrorism is linked more with developments and processes within, between, and outside the parties involved in a political conflict than with innate aggression or ideological creed. This article also draws on an analysis of Islamic Activism in a collection of essays edited by Quintan Wiktorowicz (2004), which adopts social movement theory in analyzing Islamic-oriented aggression. In analyzing the Tanzim's shift to terrorism in its conflict with Israel, the paper draws implications for countering terrorism as a strategy for CA rather than an ideology. 1 figure, 6 notes, and 40 references