Soil organic matter (SOM) is well known to exert a great influence on physical, chemical, and biological soil properties, thus playing a very important role in agronomic production and environmental quality. Globally SOM represents the largest terrestrial organic C stock, which can have significant impacts on atmospheric CO2 concentrations and thus on climate. The changes in soil organic C content are the result of the balance of inputs and losses, which strongly depends on the processes of organic C stabilization and protection from decomposition in the soil. This session will provide a forum for discussion of recent studies on the stabilization and sequestration mechanisms of organic C in soils, covering any physical, chemical, and biological aspects related to the selective preservation and formation of recalcitrant organic compounds, occlusion by macro and microaggregation, and chemical interaction with soil mineral particles and metal ions.