Youth suicide is one of the most serious preventable health problems in the United States. It is the third leading cause of death among adolescents. According to a recent national survey of students in grades 9-12, nearly 15% of respondents had seriously considered suicide and 7% actually had attempted suicide in the previous 12 months. Moreover, suicide can be a contagious behavior that schools have the opportunity--and responsibility--to prevent. Providing assistance in the aftermath of a youth suicide requires a delicate and well-planned approach; responding to the occurrence of multiple youth suicides provides an even greater challenge. The delivery of crisis response services in the aftermath of a youth suicide is referred to as "suicide postvention", which is defined as "the provision of crisis intervention, support and assistance for those affected by a completed suicide." Of primary concern following a youth suicide is the potential for contagion that can lead to cluster suicides. Contagion is the process by which the suicidal behavior or a suicide influences an increase in the suicidal behaviors of others. This article discusses the risk of contagion, how to identify and avoid contagion, and how to contain the spread of self-destructive behavior before contagion takes hold. The author emphasizes the role of principals in the early recognition of indicators that may promote the process of contagion. The author stresses that recognizing and addressing suicide contagion are essential to successful suicide postvention efforts.