The last five years have seen an increase in the recognition among scholars, school administrators, and parents that bullying among American students occurs at great frequency. One survey of over 15,000 youth found that 30% reported frequent involvement in bullying. This article provides an introduction to the topic of school-based bullying. It begins with a definition of bullying as a subtype of aggression and discusses the bully-victim continuum. The social-ecological perspective views bullying as a ecological phenomenon that is established and perpetrated over time as a result of the complex interplay between the individual child, their family, peer group, school, and community as well as their culture. Using this perspective, individual characteristics of the students as well as environmental and school factors are explored.