Bullying is one type of violence that threatens a youth's well-being in schools and neighborhoods. The impacts of bullying are felt by individuals, families, schools, and society and may result in youths feeling powerless, intimidated, and humiliated by the aggressive acts of other youth(s). This document is designed as a tool to help organizations, researchers, evaluators, community groups, educators, and public health officials define and gather systematic data on bullying to better inform research and prevention efforts. It is intended to improve the consistency and comparability of data collected on bullying. Current efforts to characterize bullying vary considerably. The lack of a uniform definition hinders the ability to understand the true magnitude, scope, and impact of bullying and track trends over time. Consistent terminology with standardized definitions is necessary to improve public health surveillance of bullying and inform efforts to address bullying. The current definition applies to bullying that occurs between peers and excludes abuse perpetrated by adults against children or youths. It also excludes family violence and violence that occurs within the context of an intimate or dating relationship. These different forms of violence (e.g., child maltreatment, sibling violence, teen dating violence, intimate partner violence, elder maltreatment) can include aggression that is physical, sexual, or psychological (e.g., verbal, belittling, isolating, coercive). However, the context and uniquely dynamic nature of the relationship between the victim and the perpetrator in which these acts occur is different from that of peer violence. This document is divided into four sections, the first of which provides background on the problem, including what is presently known about the public health burden of bullying and the need for a uniform definition of bullying. The uniform definition and description of key terms is presented next followed by considerations to keep in mind when gathering data on bullying. The last section provides a list of recommended data elements designed to assist individuals collecting information on bullying and to serve as a technical reference for the collection of surveillance data. The data elements are grouped into "core" and "expanded" data elements. Core elements are those which are recommended for inclusion in data collection systems in order to track the magnitude, scope, and characteristics of the bullying problem and to identify groups at high risk for being bullied. Expanded data elements are included to support users who may wish to collect other important contextual information about bullying (i.e., witnesses' responses to bullying) depending on community needs, interests, and the feasibility of gathering additional data. A large number of expanded data elements are provided with the expectation that the vast majority of users will only use a subset of them. The appendix contains "Family Educational Rights and Privacy Act (FERPA) and the Protection of Pupil Rights Amendment PPRA". Additional References are provided with some tables.