Based on a literature review, this web resource first distinguishes bullying from other types of aggression or violence and then presents sections on the following bullying-related topics: 1) scope of the problem; 2) theoretical foundation; 3) risk and protective factors; 4) consequences of bullying; 5) moderators and interactive protective factors; 6) bystanders; and outcome evidence for anti-bullying programs.
Bullying involving children and youth has become a topic of national conversation over the past few decades and is a major focus for schools across the United States and internationally (Gladden et al., 2014; Ybarra et al., 2019). Bullying can cause substantial harm to the children and youth who are victimized, to those who engage in bullying behaviors, and to the bystanders who witness bullying (Evans et al., 2018; Gladden et al., 2014; Zych, Farrington, and Ttofi, 2019). To address this problem, numerous antibullying interventions have been developed and implemented (Gaffney, Ttofi, and Farrington, 2019; Polanin et al., 2021). Along with these efforts, there has been a growing field of research on bullying, which strives to understand the causes, effects, and ways of effectively intervening and preventing bullying (National Academies of Sciences, Engineering, and Medicine, 2016). While multiple definitions of bullying are used in research (Eriksen, 2018; Gladden et al., 2014; Liu and Graves, 2011; Smith et al., 2002; Polanin, 2012; Younan, 2018), bullying is generally considered to be unwanted aggressive behavior(s) by another youth or group of youth (who are not current dating partners or siblings) that involves a power imbalance and is repeated multiple times or is highly likely to be repeated (Gladden et al., 2014). Although attention to bullying has increased noticeably among researchers since the late 1990s, and many studies have been published, bullying research is still considered "underdeveloped and uneven" (National Academies of Sciences, Engineering, and Medicine, 2016, p. 31). This literature review focuses on bullying that involves children and youth in elementary, middle, and high schools. The review summarizes research related to the scope of bullying in the United States; different types of bullying; theoretical foundations; predictors, risk factors, protective factors, and consequences of bullying; and interventions focused on prevention and/or reduction. Challenges and gaps in the literature are also identified.