This article includes a fairly concise summary at the end of some of the signs to look for when trying to identify both bullies and victims. I don’t entirely agree with the emphasis the writer places on television as a motivator toward bullying, but I do agree that a safe, nurturing home environment is vital for both bullies and victims, and that a home environment that lacks these things can lead to lifelong emotional/psychological damage. Also, note that what the writer refers to as passive bullying is more commonly identified as reactive aggression in the professional literature.
Emily Bazelon has done a great deal of work in the field of bullying and bullying prevention. Her book, Sticks and Stones, is well worth a read. In this interview, Emily talks about the difference between drama and true bullying, about Facebook, and about the importance of teaching empathy and moral character as well as academics.
According to this study (pdf), “the effects of being bullied are direct, pleiotropic, and long-lasting, with the worst effects for those who are both victims and bullies.” Students who have been bullied “have a higher prevalence of agoraphobia, generalized anxiety, and panic disorders.” And those who were both bullies and bullied “were at an increased risk of young adult depression, panic disorder, agoraphobia, suicidality, and antisocial personality disorder.”