Screen media now dominate the free time of children and adolescents, displacing not only healthy activities such as sufficient sleep but also risky behaviors such as substance use and unsafe driving. Screen habits and experiences play an increasingly vital role in the mental health of youths and their treatment, for better or worse. Evidence suggests that screen media played an important role in increasing the rates of depression, anxiety, self-harm, and suicide among youth in recent years. Social media offers easy, accessible interactions for anxious youth, the consequences of which vary. Screen media exposure may increase the risks of depression, anxiety, and self-harm, depending on the nature of online experiences and interactions. Viewing idealized images via social media can damage self-esteem and encourage disordered eating behavior. Research is beginning to reveal which youth are likely to benefit or suffer from specific screen habits. Digital therapeutics and online psychoeducational programs show significant promise but are limited by inherent weaknesses. Continued research is vital to inform how to guide youth to benefit from online technology without falling victim to its mental health pitfalls.