Microbiomes, the microbial communities associated with macro-organisms, are highly diverse, temporally dynamic, and variable across host species. Microbiomes can also exert strong effects on host fitness, generating optimism that they can be used to predict host dynamics. However, there have been few attempts to place microbiome-host interactions into a theoretical context. Those that have generally explore the effects of individual components of the microbiome, such as pathogens or mutualists, but such models are limited in their ability to handle the complexity and diversity within microbiomes. Plant-soil feedback theory integrates the effects of the entire belowground microbiome into patterns of plant community structure and dynamics. Since its inception 20 years ago, there has been growing evidence for and interest in plant-soil feedback as a major factor structuring plant communities. We feel that the strength of the plant-soil feedback approach, including the tight linkage between theory and experiments, offers solutions and lessons for our understanding of how microbiomes structure host communities more generally. To aid this goal, this symposium is specifically designed to foster synthesis between theory and empirical work. Our speakers will i) provide an overview of plant-soil feedback theory, its extension to empirical studies, and impact on plant community structure, ii) delve into novel extensions of plant-soil feedback theory that help us understand how plant-soil feedback influences population dynamics and species coexistence, iii) provide new examples of how we can test plant-soil feedback theory and its influence on plant community properties, and iv) discuss general patterns, lessons learned, and future directions for plant-soil feedback research. Uniting these perspectives and approaches can inform how ecological communities are structured and provide insights into how plant communities may respond to a changing world. Our hope is that this symposium and the discussion it stimulates will be the basis for creating a better understanding of how to incorporate the microbiome into host dynamics and pave the way for further advances in plant-soil feedback research.