Nearly every young person spends a large part of their life in online spaces. On social media platforms, in digital games, and in augmented-, virtual-, and mixed-reality environments, they are exposed to a vast range of content with unlimited opportunity to engage with other users. For many young people, these interactions are ongoing and frequent, creating a second social universe largely unseen by the adults in their lives. With young people’s rising rates of mental health problems, including depression and suicidal ideation, it is critical to investigate the impacts—positive and negative—that online spaces have. The picture is complicated, and the evolution of the metaverse adds another layer that has not been investigated. The U.S. Surgeon General has called on the country to take a “safety first” approach to the online lives of youth, prioritizing evidence-based research into “the impact of social media on children and adolescents.”