Dealing with relationship drama is a universal part of the American teen experience. Mean girls are such a ubiquitous part of the experience we feature them in books, movies, and Broadway shows. [a] While generally the focus has been on mean girls, we know now that mean boys also exist. Scientists refer to the phenomenon of mean girls (and boys) as relational aggression.
Relational aggression is aggression that is intended to harm another adolescent. Instead of punching, kicking, or getting in a fight, relational aggression uses the manipulation of social standing and social relationships to inflict harm. It means ignoring somebody, spreading rumors, breaking up friendships, telling lies – all to achieve the goal of hurting somebody and affecting their (or your) social standing. In other words, relational aggression is wielded to climb the social ladder, or to make others fall. In adolescence, individuals who use relational aggression are likely to be high status within their peer group. 
For decades, the study of aggressive behavior was limited to physically aggressive behavior, which is primarily carried out by boys. In the 90s, scientists turned to the study of aggression that girls are more likely to engage in: using the social world around them to inflict injury. Turns out that aggression – physical or relational – follows the same trajectory over time: it increases during early adolescence and then declines from mid-adolescence into the 20s.  [b] It’s also true that teens that are aggressive in one way are aggressive in other ways. So the boys who get in the schoolyard fights are more likely to be mean to other kids. The girls who spread rumors are more likely to throw a punch.
On interesting fact about parenting and relational aggression is that the same types of parenting that contribute to a teen being very physically aggressive are related to a teen using relational aggression. Parents who are harsh (i.e., not warm) and controlling of their child’s behavior tend to have teens that engage in more relational aggression.  In contrast, parents who are warm and firm (but not rigid) tend to have kids who have the lowest aggression. Ideally, in the teen years, parents strike a balance of being loving and caring, which encourages trust and open communication. With respect to rules, excellent parents set boundaries for their teen, but can be flexible in these boundaries if need be. The example I always give is prom night. Parents should recognize that prom night is a different night than other nights, and should have a conversation with their teen about whether or not extending curfew is appropriate. It doesn’t mean that you have to agree to your teen’s demands – but having a conversation where both parties are heard is important.
Beyond parenting, how can we help teens use relational aggression less? Some have argued that school based programs are the answer. These programs provide teachers with information about understanding and preventing relational aggression. Other programs focus on changing student attitudes in a school, helping them to identify relational aggression and to provide strategies to resolve it. Changing student attitudes about relational aggression, namely that it is unacceptable, are important because if teens think it is okay to engage in relationally aggressive behavior, they are more likely to do it.  In general, dealing with these issues earlier in adolescence seems to be better. Since relational aggression increases in early adolescence, most experts agree that middle school is the time to intervene.
Of course, people have to want to change. And this turns out to be hard. Relational aggression is used to attain status. When you get what you want, you are likely to keep doing it. It’s a very Machiavellian argument – but for teens, the ends often justify the means. Remember, kids who use relational aggression tend to have higher status in the peer group,  which essentially rewards them for the aggressive behavior. One way to help teens to use less relational aggression is to start early and to be consistent and vocal about our dislike of the behavior. If a youth hit somebody we would react by explaining why that behavior was bad. We should do the same for excluding others from the group, with holding friendship, and spreading rumors.
[a] In the early 2000s two books on relational aggression in females were best sellers: Queen Bees and Wanabees, Wiseman, 2003, Odd girl out, Simmons, 2003. These books were the basis for the movie, Mean Girls, 2004, which was recently turned into a Broadway musical.
[b] Aggression against peers doesn’t come out of thin air. We see the beginnings of it in middle childhood. Read here for more.
 Cillessen, A. H., & Mayeux, L. (2004).
 Nylund, K., Bellmore, A., Nishina, A., & Graham, S. (2007); Card, N. A., Stucky, B. D., Sawalani, G. M., & Little, T. D. (2008); Karriker-Jaffe, K. J., Foshee, V. A., Ennett, S. T., & Suchindran, C. (2009).
 Kawabata, Y., Alink, L. R., Tseng, W. L., Van Ijzendoorn, M. H., & Crick, N. R. (2011).
 Werner, N. E., & Nixon, C. L. (2005).
 Rose, A. J., Swenson, L. P., & Waller, E. M. (2004).