In over two decades of social media (SM) and constantly increasing user accounts, it is unquestionable that SM has taken an ever more important stand in society, combining various functions for communication and entertainment. SM represents a powerful tool to promote healthy behaviors to a larger public audience and hence, has the potential to be integrated into digital public health (DiPH). Using this potential requires a profound understanding of the potential impact of SM on health, well-being, and related behaviors. This chapter, therefore, discusses the impact of SM on DiPH, with a particular focus on the vulnerable group of children and adolescents. This chapter considers three perspectives: First, epidemiological studies show that SM exposure has a negative impact on children’s and adolescents’ diets and can further contribute to addiction, psychosocial distress, and depressive symptoms. Second, from the perspective of Human-Computer Interaction (HCI), SM provides interface strategies such as dark patterns that trick users into unwanted interactions, which may lead to increased screen time, and could thus worsen the adverse health outcomes. Third, from a legislative perspective, we explore how European and mainly German laws protect vulnerable groups in the SM environment.