Rapid advances in human microbiome research point to an increasing range of health outcomes related to the composition of an individual’s microbiome. To date, much research has focused on individual health, with a paucity of attention to public health implications. This is a critical oversight owing to the potentially shared nature of the human microbiome across communities and vertical and horizontal mechanisms for transferring microbiomes among humans. We explored some key ethical and social implications of human microbiome research for public health. We focused on (1) insights from microbiome research about damage to individual and shared microbiomes from prevalent societal practices, and (2) ethical and social implications of novel technologies developed on the basis of emerging microbiome science.