This chapter reviews the objectives of and educational, motivational, and skill-building components of bystander intervention training programs. Influences on each step of the decision-making process, relevant competencies, and corresponding interventions are summarized in a figure. The effectiveness of bystander intervention programs focused on preventing sexual violence, as well as those addressing bullying and cyberbullying, is detailed. Examples of bystander intervention programs to prevent sexual violence and bullying are described. Considerations for bystander intervention programs, including models for dissemination, cultural responsivity, use of technology, and the role of empathy training, are offered.