Social media use has become so pervasive in the lives of American teens that having a presence on a social network site is almost synonymous with being online. Fully 95% of all teens ages 12-17 are now online and 80% of those online teens are users of social media sites. The authors focused their attention in this research on social network sites because they wanted to understand the types of experiences teens are having there and how they are addressing negative behavior when they see it or experience it. As they navigate challenging social interactions online, who is influencing their sense of what it means to be a good or bad "digital citizen"? How often do they intervene to stand up for others? How often do they join in the mean behavior? Many log on daily to their social network pages and these have become spaces where much of the social activity of teen life is echoed and amplified--in both good and bad ways. In their survey, the authors follow teens' experiences of online cruelty--either personally felt or observed--from incident to resolution. The authors asked them about how they reacted to the experience and how they saw others react. They asked them about whether they have received and where they sought advice--both general advice about online safety and responsibility and specific advice on how to handle a witnessed experience of online cruelty on a social network site. They also probed the environment around teens' online experiences by examining their privacy controls and practices, as well as the level of regulation of their online environment by their parents. The authors further sought insight into more serious experiences that teens have in their lives, including bullying both on- and offline and the exchange of sexually charged digital images. (Contains 2 tables and 57 footnotes.)