European new social movement (NSM) theory was developed to describe and explain the apparently unique character of the wave of collective action that began in the 1960s and continues to this day. Key characteristics of NSM theory are a post-industrial orientation, middle-class activist core, loose organizational form, use of symbolic direct actions, creation of new identities, and a 'self-limiting radicalism'. The theory's claims to movement innovation were later criticized by many as exaggerated and ahistorical. However, the filtering down of key NSM elements into social movement studies has led to changing definitions of what social movements actually are and opened up new opportunities for the integration of religious movements into the social movements mainstream. Using the case of radical Islam, and with particular reference to the terrorist social movement organization al-Qa'ida, this article argues that drawing on key features of NSM theory should lead to a better understanding of radical Islam as well as a more realistic explanation of its continuing development and transformation.