Direct and indirect aggressive behaviors were studied using surveys and interviews of students in two public schools. The variables of "sex-of-aggressor" and "sex-of-target were included. Claims in previous research that girls engage in far more indirect aggression than boys are not supported. Further, it was found that girls are more likely to target the opposite sex with direct aggression than boys. This suggests more gender fluidity in the use of aggression by girls and adds to a growing body of research that dispels the notion that direct and indirect aggression can be neatly sorted into male and female categories of behavior.Keywords: aggression, sex differences, direct aggression, indirect aggression, prevalence and preferences for forms of aggression, sex of target 1 This article reports on research that calls into question the notion that the use of aggression and violence can be neatly categorized according to sex and that girls generally employ indirect forms of aggression while boys generally employ direct forms of aggression.Whether the focus of inquiry is physical or verbal observable aggression, as it was for much of the twentieth century (Vaillancourt 2005), or non-observable aggression (a form of aggression that has garnered much interest especially in those focusing on female use of aggression), Gendreau and Archer (2005) Research on non-observable aggression like shunning, deliberate exclusion, gossip or rumor mongering, the silent treatment and the like, has thus far employed three different concepts or terms (see Vaillancourt, 2005 for a thorough discussion). The first of these three concepts is relational aggression, a term coined by Crick (1993) to refer to behaviors used to damage other people's relationships, feelings of acceptance, and social inclusion. Relational aggression has also been applied to behaviors like a) indirectly excluding or socially manipulating a person by using another's relationship with that person as the vehicle for harm (Cullerton-Sen & Crick, 2005); b) actions such as keeping 2 someone out of a group, saying you will not be friends with someone, ignoring a person, telling rumors or lies about someone you are mad at (Henington, Hughes, Cavell, & Thompson, 1998); and c) threatening to end a friendship or no longer talking to someone, and deliberately excluding someone socially (Werner & Nixon, 2005).The second term, social aggression, used by Galen and Underwood (1997), Cairns, Cairns, Neckarman, Ferguson, and Gariepy (1989), and Xie, Cairns and Cairns (2002) refers to aggressive behavior that is intended to damage another person's selfesteem but does not focus on disrupting that person's social relationships. This kind of aggression is focused more on making targets feel badly about themselves or afraid for their own safety without directly engaging in directly attacking them.The third concept, indirect aggression, coined in the late 1980s by Lagerspetz, Björkqvist and Peltonen (1988), refers to a form of aggression in which "the instigator manipulates o...