Historically, society at large has a tendency to view microorganisms as “germs”. Although microbial pathogens have important consequences for human health, they are rare compared to the diversity of beneficial microorganisms. It is well established that microorganisms control essential processes such as carbon sequestration, trace gas flux, and nutrient cycling. In addition, we rely on microorganisms for the maintenance and stability of ecosystem services. When managed properly, microbial populations can be harnessed for contaminant degradation, biofuel production, water purification, and increased food yield. When we fail to appreciate the ecological principles governing microbial dynamics, however, natural and managed ecosystems become susceptible to disease outbreaks, harmful algal blooms, and less efficient functionality. This proposed session features topics where microbial ecology contributes to management, restoration and sustainability of the biosphere. We will discuss current and emerging foci of microbial ecology and environmental microbiology in the framework of “Earth stewardship”. Conceptually, this symposium will build from the roundtable discussion that was part of a Special Session that the organizers arranged at last summer’s ESA meetings. The proposed symposium will include both broad overviews as well as case studies presented by researchers from a variety of disciplines (i.e. engineering, ecological theory, biofuels, sociology) whose research addresses the importance of microorganisms in sustainability and stewardship. The symposium will begin with an overview of the role of microbial communities in ecosystem services, followed by examples from both natural and managed ecosystems highlighting the myriad ways in which microbial communities influence environmental quality and sustainability. The presentations will illustrate how microbial ecology is currently integrated into complex social-ecological systems, and foster discussion on how we could better apply ecological theory to harness microbial communities and their processes. The symposium will begin with a 5 minute introduction, followed by a 25-minute tutorial addressing microorganisms and ecosystems services. This will be followed by eight 15-minute presentations with 5 minutes for questions between each oral presentation. Highlights from these oral presentations will be proposed to “Frontiers in Ecology and the Environment” as a review article or special issue for publication.