This report provides basic background information on the reason why some Muslims become radicalized, why some will go further and join radical organizations and others still will go further and commit criminal acts in support of, or directly committing terrorism. It is split into three sections and begins with a general overview of the demographics as well as the political, economic and social challenges facing Muslims in the European Union. In the second section, a process of radicalization is mapped out and related back to the issue of integration. The third section analyzes the phenomenon of so-called “homegrown” terrorism by putting it comparative perspective with violent domestic extremist groups. Finally, this report ends with a series of policy recommendations to law enforcement communities, American Muslim communities, and local, state and federal governments