This chapter highlights key themes from this book related to bystander intervention in bullying and peer victimization. It emphasizes that bullying is a social phenomenon often reinforced by peer dynamics, and the role of bystanders is critical in addressing it. Factors such as individual traits, peer influence, and school context, that influence each step of the bystander intervention model, are summarized. The chapter reviews both the potential risks and benefits of intervention, along with direct and indirect strategies. The research-based framework guiding bystander decision-making is reviewed in relation to training that can empower students to recognize bullying, take responsibility, and act. Bystander intervention is discussed within broader bullying prevention efforts, including the role of educator intervention and the use of multi-tiered systems of support. Special attention is given to unique challenges in digital environments and in addressing microaggressions. The chapter concludes by identifying areas for future research, with a particular focus on methodological advances.