Bullying and victimization remain significant problems among school-age children (Cook et al., 2010). Greater understanding of this behavioral process is necessary to create more effective interventions and treatments toward the goal of improving the quality of life for children. One theory of bullying is the compensation model of aggression (Nail, Bihm, & Simon, in press; Staub, 1989). It proposes that bullying is driven primarily by the personality of the bully, as bullies attempt to compensate, or make up for, their own feelings of weakness and vulnerability by dominating others. Essentially, the bully's feelings of insecurity are thought to be turned outward and converted into aggression against others-typically those who are physically weaker and readily available, such as smaller classmates (Kaukiainen et al., 2002) or a bully's spouse (Gondolf, 1985). The compensation model has been supported by a number of studies that have found a positive correlation between a defensive personality structure and bullying or aggression in schools (e.g., Nail et al., in press; Sandstrom & Jordan, 2008). Defensive personality can be operationally defined in various ways, but one is defensive egotism-i.e., students who think too highly of themselves and always want to be the center of attention. A major problem with the support for compensation model, however, is that almost all of the findings to date have been correlational in nature, whereas the model proposes that a defensive personality causes bullying. The proposed research will address this problem. It is well established in the literature that manipulated laboratory threats can cause increases in aggression, especially for those with a defensive personality structure (e.g., Bushman et al., 2009). It is also well established that threat-induced defensiveness can be reduced or eliminated by interventions that allow people to affirm core aspects of their self image (e.g., McGregor, Nail et al., 2005). What is not known is whether self-affirmation interventions can cause decreases in bullying. The defensive egotism of seventh graders will be assessed by the reports of their classmates and teachers. Later on a Monday morning, randomly chosen students will write an essay explaining (a) why their most important values are important to them (viz., self-affirmation participants) or (b) why their least important values migt be important to others (non-self-affirmation/control participants). On Friday afternoon of that week, students and teachers will report the dependent variables-the bullying and aggression of their classmates and students, respectively, over the past week. If the compensation model is correct, only non-self- affirmation/control participants will show the usual positive link between defensive egotism and bullying/aggression. Self-affirmation participants should have little need to feed their ego by bullying others that week because their self-concept will have been bolstered by the writing task. Such findings will point to the need for a more holistic model of bullying reduction-one that combine's current whole-school, administrative efforts with targeted, therapeutic interventions for bullies.