The nature and extent of bullying among school children is discussed, and recent attention to the phenomenon by researchers, the media, and policy makers is noted. The Olweus Bullying Prevention Program (OBPP) is a comprehensive, school-wide program that was designed to reduce bullying and achieve better peer relations among students in elementary, middle, and junior high school grades. Several large-scale studies from Norway are reviewed, which provide compelling evidence of the program's effectiveness in Norwegian schools. Studies that have evaluated the OBPP in diverse settings in the United States have not been uniformly consistent, but they have shown that the OBPP has had a positive impact on students' self-reported involvement in bullying and antisocial behavior. Efforts to disseminate the OBPP in Norway and the United States are discussed.