The fields of crisis theory and crisis intervention have experienced renewed interest in the wake of disastrous events such as school shootings and terrorist attacks. Since many personal and community crisis events require an official response, social service and criminal justice agencies assume the majority of the responsibility for providing crisis intervention. The authors define “crisis” and discuss the characteristics of people who may be particularly vulnerable to a crisis. The origins and foundations of crisis theory, which dates back to the 1920s, are explored and the early research on the experiences of, and responses to, crisis is presented. Different types of individual crises are identified before the authors move along to a consideration of the community’s responsibility for crisis intervention. Community engagement in crisis intervention has recently taken the form of school safety programs, domestic terrorism response, and hate crime victimization services. Even as the community takes greater responsibility for crisis intervention, the treatment focus has been retained and remains a large part of the operations of formal crisis intervention agencies such as the American Red Cross. The interpersonal communication skills necessary for successful crisis intervention are discussed and the crisis assessment process, which focuses on the evaluation of the client, is reviewed. The five phases of the crisis intervention process are outlined: information gathering, control, direction, progress assessment, and referral. The authors conclude the chapter with discussions of the role of crisis intervention within criminal justice and social services, the importance of a culturally sensitive approach in crisis intervention, and the government’s role in promoting crisis intervention. The importance of crisis intervention training across all sectors of the criminal justice system and social services is underscored as the authors discuss the benefits of crisis intervention for victims and offenders alike. Chapter questions and exercises are included. Appendix, references