Mutualistic associations, in which partner species exchange resources or services, are ubiquitous in nature and can ultimately result in dramatic fitness benefits for participating organisms. However, these interactions do not happen in isolation, but rather occur in the complex contexts of populations, communities, and ecosystems. Not only can these contexts have a substantial effect on the outcome of mutualistic associations for the participating organisms, these associations can ultimately affect higher order processes, such as population dynamics, community assembly, and ecosystem function, though not necessarily in ways that might be predicted. For example, does engaging in a mutualism translate to greater population size, community dominance, or ecosystem engineering for a species? Might there be hidden costs to mutualism that prevent scaling the benefits to higher order processes? Do mutualists substantially impact fundamental ecological processes and properties like succession and productivity-diversity relationships? And, do these changes to higher order processes have important consequences for the restoration and conservation goals? In this organized session, speakers will explore the many other ways that the effects of mutualisms scale to these higher order processes and the simultaneous influence of higher order biological processes on these interactions. We have chosen to focus this session on plant-microbe mutualisms (e.g., fungal endophytes, arbuscular mycorrhizal fungi, and rhizobia) in light of the tremendous diversity and abundance of these hidden players that are increasingly recognized, characterized, and quantified with the recent advent of sequencing technologies. This session will synthesize the broad effects of mutualisms beyond the two partnered individuals in order to understand the larger impacts mutualisms play in ecological systems. We intend for the session to have broad appeal for researchers interested in species interactions, microbes, plants, ecological complexity ranging from individuals to ecosystems, and applied goals of restoration and conservation.