In order to employ strategies to prevent the development of criminal or violent youth gangs, it is necessary to know what gangs are or what they are not and what they do. This paper presents a description and understanding of gangs in Australia, specifically answering the questions: (1) what is gang-related behavior; (2) are all gangs the same; and (3) how do groups or gangs change over time? Findings can be applied across assorted geographic, demographic, and ethnic settings. The findings include: (1) gangs are diverse; (2) gangs change and evolve due to direct factors and in response to indirect factors; (3) reactions to gangs vary, in that some communities deny they exist while others sensationalize them; and (4) effective responses to gangs are diverse, such as prevention, intervention, suppression, or enforcement. Practical examples and case studies from diverse jurisdictions can offer invaluable insights in knowing how to respond to perceived gang problems. References