Threat assessment is a method used by mental health and law enforcement professionals to assess the risk of intended violence toward a specific target, such as attacks and assassinations of public figures, workplace homicides, mass murders, school shootings, and acts of terrorism, both domestic and foreign. Beginning with studies by the U.S. Secret Service twenty years ago, the research and interest in this field has accelerated over the past decade with published scholarship and emerging professional organizations. International Handbook of Threat Assessment offers a definition of the foundations of threat assessment, systematically explores its fields of practice, and provides information and instruction on the best practices of threat assessment. The volume is divided into three sections. Section I defines the difference between threat assessment and traditional violence risk assessment and discusses threat assessment terminology and practice, contemporary understanding of threats, warning behaviors concerning targeted violence, and the legal basis of threats and targeted violence interventions. Section II elaborates on the various domains of threat assessment, such as workplace violence, public figure attacks, school and campus violence, insider threats, honor-based violence, computer-modeling of violent intent, targeted domestic violence, anonymous threats, and cyberthreats. Section III presents the functions of a number of threat assessment individuals and units, including the UK Fixated Threat Assessment Centre, the LAPD Threat Management Unit, Australia's Problem Behaviour Program, and the U.S. Navy Criminal Investigative Service, among others. This book will serve as the standard reference volume in the field of threat assessment and will be invaluable to mental health and criminal justice professionals who practice threat assessment or are interested in understanding this new field of research.