Plant–soil feedbacks are legacy effects created by an initial plant on the growth of subsequent plants using the same soil. These indirect soil-mediated interactions are primarily studied in the context of changes in the belowground biotic community. Here, we review current evidence surrounding plant–soil feedbacks, focusing on how these interactions are studied from an experimental standpoint and expand this discussion into new directions surrounding the influence of feedbacks on interactions with aboveground herbivorous insects. The taxon-specific impact of individual soil groups on foliar-feeding insects is well-described, but expanding this framework to plant–soil feedbacks is challenging because different plant species cause simultaneous and dramatic shifts in the composition of all soil life, sometimes in contradictory directions (i.e., certain fungi may increase, while nematodes decrease). Thus, expanding simple pair-wise root herbivore–plant–insect relationships to more holistic approaches that account for the full spectrum of changes in soil biota represents both a mechanistic and analytical challenge. These community-wide shifts, however, are representative of true legacy effects encountered by plants and insects in nature. We end our chapter on a discussion of how plant–soil feedbacks can be functionally used to steer the microbiome for enhanced crop protection in applied agricultural systems.