Social media and youth mental health have a relationship that many have great interest in understanding. Recent legislative bills in the United States have focused on curbing the potentially harmful effects of social media use, and large social media companies are under related litigation. The current chapter summarizes the research on social media use and youth mental health to provide the reader with a solid background of the major studies in the field. In general, the research is mixed, nuanced, and complex with a number of factors contributing to adolescent outcomes, including the content viewed, the context of social media, with whom the adolescent is interacting, and individual differential susceptibility. Future avenues for research are discussed with a focus on understanding both risk and protective factors of using social media on youth mental health, determining temporality, and understanding differential susceptibility, particularly with regard to minoritized youth. Finally, we offer specific recommendations for clinical practitioners and providers, policymakers, educators, and parents.