Book excerpt: Understanding Gangs and Gang Violence in America examines past, current, and future concerns regarding street and prison gang life in the United States. Author Gabe Morales combines his personal history, his experience serving in the adult and juvenile criminal justice system, thought-provoking case studies, and the perspectives of other experts within the field to paint a comprehensive and holistic portrait of American gangs and gang violence. The text examines what a gang is, how gang members are defined by various segments of society, common forms of gang communications, and the rules of the streets. It covers the history of major gangs in America, gang recruitment and behaviors, hate groups, and prevention and intervention programs. Dedicated chapters discuss teen brain function and risk factors for gang involvement, national and local responses to gang activity, and the efficacy and inefficacy of state laws. The book concludes with a discussion of gangs on an international scale, the future of gang-related issues, and how readers can apply their knowledge at the community level. Understanding Gangs and Gang Violence in America is valuable for courses in criminal justice and corrections. It can also be used by criminal justice and law enforcement practitioners who work with at-risk or gang-related populations.