This article will argue that social media in the hands of terrorist groups constitutes a weapon, and has become increasingly capable of contributing to the facilitation of consequential harm against identified targets. In doing so it will first clarify the communicative nature of terrorist action and provide an overview of the various contributions made by jihadist strategists to the evolution of terrorist practice, and in particular the re-emergence of the practice of individual terrorism. It will then identify the intersection of individual terrorism and social media and the development and deployment of a system of social media jihad. The article will explain the mechanisms by which terrorist groups exploit and deploy social media platforms, and inflict various harms, with a specific focus on individual and small cell terrorism in Western jurisdictions. Finally, a brief case study analysis of Anwar al-Awlaki will demonstrate the gravity with which governments have conceived of this problem, in part by highlighting the substantiveness of their responses.