Adolescents and young adults are avid Internet users. Online social media, such as social networking sites (e.g., Facebook, MySpace), blogs, status updating sites (e.g., Twitter) and chat rooms, have become integral parts of adolescents' and young adults' lives. Adolescents are even beginning to enter the world of online dating with several websites dedicated to "teenage online dating." This paper reviews recent peer-reviewed literature and national data on 1) adolescents use of online social media, 2) gender differences in online social media and 3) potential positive and negative health outcomes from adolescents' online social media use. We also examine parental monitoring of adolescents' online activities. Given that parental supervision is a key protective factor against adolescent risk-taking behavior, it is reasonable to hypothesize that unmonitored Internet use may place adolescents' at significant risk, such as cyberbullying, unwanted exposure to pornography, and potentially revealing personal information to sexual predators.