Technical Abstract: Soil microbial communities are comprised of a vast array of bacteria, fungi, nematodes and other organisms. It is becoming increasingly clear that these communities are not passively determined but actively regulated by plants. This chapter discusses the role plant root exudates play in the active regulation of soil microbial communities. In addition we discuss the potential role co-adapted plant-soil microbial communities may play in agricultural sustainability and production. We suggest that minimal disruption in the plant-microbial community should be maintained in order to achieve maximum long-term agricultural production by minimizing disease outbreaks and by reducing costly agricultural inputs such as pesticides and fertilizers.