This edited book presents international perspectives on the role of mental health problems in understanding and managing the risk of violent extremism. The chapters included in this book address two themes. First, they describe the research findings on the nature and prevalence of the range of mental health problems (psychosis, personality disorder, post-traumatic stress disorder, anxiety and depression, autism spectrum disorders) in young people and adults who have in the past, committed acts of violence motivated at least in part by extremist ideologies, or who have attempted or threatened such acts, or who for other reasons are thought to be at risk of doing so. Second, the chapters examine what is known about the relationship - or the functional link - between mental health problems and violent extremism. The focus of this book is on clinical practice and understanding the nature of the challenge faced by practitioners and their response to it. It will therefore be of interest to mental health practitioners, service managers and commissioners, and policy makers with a remit to understand and mitigate risk of radicalisation and violent extremism. The chapters in this book were originally published in The Journal of Forensic Psychiatry & Psychology.