The study found that both defenders and outsiders in bullying episodes had high levels of empathy. What distinguished their contrasting behaviors was the level of social efficacy. High levels of social self-efficacy (i.e., confidence and assertiveness in managing social environments) were linked to defenders; whereas, low levels of social self-efficacy (i.e., more timidity and reserve in managing social environments) were linked to passive bystanding behavior. Since the large majority of students did not approve of bullying and expressed admiration for peers who actively intervened to stop it, the authors suggest training youth to intervene against bullying in effective ways that will not jeopardize their own safety. Assertiveness training exercises are suggested. A total of 294 Italian students (47.2 percent girls) voluntarily participated in this 2005 study. They attended a middle school that served a low middle-class community in a mid-sized city in northern Italy. Participants were asked to nominate up to five classmates who fitted each of the behavioral descriptions in bullying situations presented in a questionnaire. Each nominated classmate was asked to indicate whether he/she "sometimes" or "often" exhibited behaviors associated with "defenders" and "outsiders" in bullying situations. The nominated students were then administered the Interpersonal Reactivity Index in order to measure their level of empathic response to the feelings and circumstances of others. The Social Self-Efficacy Scale was used to measure participants' perception of being competent in social situations and assertive in interpersonal relationships. 1 table, 1 figure, and 66 references