Bullying and peer victimization in school are serious concerns for students, parents, teachers, and school officials in the U.S. and around the world. This article reviews risk factors associated with bullying and peer victimization in school within the context of Bronfenbrenner's ecological framework. This review integrates empirical findings on the risk factors associated with bullying and peer victimization within the context of micro- (parent-youth relationships, inter-parental violence, relations with peers, school connectedness, and school environment), meso- (teacher involvement), exo- (exposure to media violence, neighborhood environment), macro- (cultural norms and beliefs, religious affiliation), and chronosystem (changes in family structure) levels. Theories that explain the relationships between the risk factors and bullying behavior are also included. We then discuss the efficacy of the current bullying prevention and intervention programs, which is followed by directions for future research. (C) 2012 Elsevier Ltd. All rights reserved.