The decomposition and mineralization of plant litter and soil organic matter is known to be regulated by a set of hierarchically-organized interacting factors (climate, clay mineralogy, nutrient status of the soil, quality of decomposing resources and the activity of soil organisms). Although it is possible to predict decomposition and mineralization rates, the relative importance of the actual controlling factors and the mechanisms and effects of their interactions are not well understood. In particular, the interaction of the quality of resources and the soil organisms is not well understood. This dissertation presents results of field, laboratory experiments and simulation modeling that investigated some aspects of the interaction between the chemical quality of plant litter and the structure of the soil community. Chapter 2 investigates the short term effect that the chemical composition of one-time surface applied litter materials has on the soil microbial and mesofaunal communities in the mineral soil. Chapter 3 examines whether the changes brought about in soil by the quality of litter can influence the ability of the soil community to mineralize and decompose freshly added substrates and materials already present in the soil and whether the composition of the faunal community would affect this ability. In Chapter 4 we explore one potential way in which the soil fauna could affect nitrogen mineralization: by mediating the control that the quality of litter exerts on the structure of the micro-food web. Chapter 5 uses simulation modeling of soil food webs to (a) assess the importance of the soil community changes brought about by the quality of litter on carbon and nitrogen mineralization from litter and soil, (b) evaluate the whether the role of the soil communities and their trophic interactions varies depending on the quality of the degrading substrate and (c) investigate whether all soil communities are equally suited to degrade substrates of all qualities. Chapter 6 used food web modeling to test the hypothesis that taking into account the soil biota structure and dynamics in addition to litter quality is important in explaining short-term nitrogen mineralization patterns from plant litter in an agricultural system.