The report consists of two parts. The first examines all cases of U.S. persons arrested, indicted, or convicted in the United States for IS-related activities. This section also looks at the cases of other Americans who, while not in the legal system, are known to have engaged in IS-inspired behavior. The second examines various aspects of the IS-related mobilization in America. It analyzes the individual motivations of IS supporters, the role of the Internet -- in particular, social media -- in their radicalization and recruitment processes, whether their radicalization took place in isolation or with like-minded individuals, and the degree of their tangible links to IS.