These essays trace the development of the gangs, from Mara Salvatrucha to the 18th Street Gang, in Los Angeles and their spread to El Salvador, Honduras, Guatemala, and Nicaragua as the result of members' deportation to Central America; there, they account for high homicide rates and threaten the democratic stability of the region. With expertise in areas ranging from political science to law enforcement and human rights, the contributors also explore the spread of violence in the United States. Their findings comprise a complete documentation that spans sexualized violence, case studies of individual gangs, economic factors, varied responses to gang violence, the use of intelligence gathering, the limits of state power, and the role of policy makers. Raising crucial questions for a wide readership, these essays are sure to spark productive international dialogues.