Gang affiliation is not something that students leave behind when they come to school. Gang members do not leave their behaviors, attitudes, and conflicts outside the school environment. Gangs, unchecked and unidentified in a school setting, often engage in threat and intimidation; physical and cyber bullying; fighting; recruiting; and criminal activities such as the introduction and use of weapons, assault, sex trafficking, vandalism, and illegal drug sales. The absence of a well-developed, strategic, collaborative, and effective school safety plan can lead to violence and other unsafe and disruptive activities within a school setting. It is not solely the responsibility of schools to create and maintain a safe learning environment, free from the disruption gangs can cause, for students, faculty, and staff. To develop a comprehensive plan that identifies effective, evidence-based strategies to address gang issues in the school environment requires the involvement of law enforcement, school administrators and staff, and other key sectors of the community. This guide was designed to provide schools and law enforcement with sound practices and collaborative techniques to identify, assess, and address gang activity in the school setting.