This learning brief focuses on bystander interventions, with the aim of providing GBV actors with basic information about what constitutes bystander interventions and whether they may be used in humanitarian contexts. The learning brief begins with an overview of key concepts related to bystander programs, including some historical background to the evolution of bystander programming. It goes on to describe the basics of bystander interventions, with some examples of programs from around the world that have been evaluated. The brief then focuses on a few of the critical safety concerns related to implementing bystander intervention programs, and discusses key considerations for designing, monitoring, and evaluating bystander intervention programs in humanitarian contexts. The learning brief concludes with several key takeaways for GBV actors who are considering undertaking bystander intervention programming as part of the wider GBV prevention and response programming being undertaken in humanitarian settings.