This thesis focuses on the nexus between a terrorist group's narrative and the group's success or failure in achieving its strategic goals. This work theorizes that the interaction of competing narratives exerts a systematic impact on the ability of the terrorist group to achieve its strategic goals through the influence that the narratives have over a group's members, the group's adversary, and the affected population. Although a terrorist group with a good narrative can be defeated, a terrorist group with a weak narrative is much less likely to win. Consequently, in order for a terrorist group to improve its chances of prevailing, it needs a strong narrative. While issues like material shortfalls, the repressiveness of state security services, and changing demographics could contribute to the demise of a terrorist group, these factors also serve to demonstrate how difficult it is for a terrorist group with a weak narrative to generate enough support to overcome these deficits. Since narratives are not fixed, each side may choose to change their narrative in order to accurately address changing circumstances. Changes could follow shifts in policy, appointment of new leadership, and even changes of fortune.