Book excerpt: Biker Gangs and Transnational Organized Crime, Second Edition, describes and analyzes a rapidly expanding global problem: criminal acts committed by motorcycle gangs. Thomas Barker, one of the world’s top experts on outlaw biker gangs, offers fascinating details about the Bandidos, the Vagos, the Mongols, and other "one percenters" (criminal biker gangs, as opposed to the vast majority of motorcycle enthusiasts). He combines this data with a strengthened conceptual framework that makes sense of this complicated picture. U.S.-based motorcycle gangs like the Hells Angels have proliferated, especially in Canada and Europe, to the point where these gangs have more members in other countries than in the United States. Increasingly more often in recent years their crimes are not limited to rumbles or drug use—these gangs challenge the dominance of organized crime, leading to violent conflicts between the rivals. Germany, Scandinavia, the UK, the Netherlands, and Canada are particularly hard-hit by this rising violence. One of Barker’s unique contributions is his Criminal Organization Continuum, building on the groundbreaking network approach to organized crime proposed by Klaus von Lampe. Introduced in the first edition, Barker elaborates his continuum tool and makes it more multi-dimensional to help refine the definition of adult criminal gangs. The product of years of research, this book lays the groundwork for further study by offering students, police, and researchers the most thorough account available of outlaw motorcycle gangs.