Disruptions to the microbiota can have pathological consequences, which highlights the need to understand the factors that contribute to its stability. Although decades of research have focused on the importance of IgA during pathogenic infection, much of the IgA that is generated in the gut targets the resident commensal microorganisms. Despite this observation, the role of antibodies in regulating microbiota composition remains controversial and poorly understood. Here we propose that antibodies generated in response to microbial colonization of the gut shape the composition of the microbiota to benefit the health of the host through a process that we term antibody-mediated immunoselection (AMIS). Given the exquisite specificity of antibodies and an emerging interest in the use of immunotherapies, we suggest that understanding AMIS of the microbiota will highlight novel uses of antibodies to manipulate microbial communities for therapeutic benefit.