Bullying and associated behaviors are a growing problem at all levels of development. Typically, establishing whether or not an incidence of bullying or associated behavior (i.e., victimization, relational aggression, physical aggression, etc.) has occurred in a school setting is not inherently problematic, but once the behavior is detected, determining the level, severity, or prevalence of the behavior is not so straightforward. In addition, something must be done to change or eliminate the negative behaviors, resulting in the need to be able to accurately determine whether behavior has truly been changed. Th us, a considerable amount of research in school bullying involves determining the level of behavior and assessing change in behaviors at the individual student level. Th is can be as straightforward as determining that a student engaged in a pattern of negative behavior deemed to constitute bullying, and following corrective disciplinary action or re-education, the student’s pattern of negative behavior was altered in a positive direction. In a broader prevention context, determining the level of and change in bullying behavior may involve a pre-post quasi-experimental design where the behavior is detected as generally present in a sample of students, some intervention is applied, and the level of the behavior is re-assessed. In other developmental contexts, researchers or practitioners may be interested in tracking changes in behavior over a period of time in order to determine the overall natural pattern of the behavior.