Predicting soil C responses to land use and management practices involves integrating the effects of processes adding organic carbon to soils and processes that determine the residence time in soil of added carbon, as a function of decomposition processes and the stabilization of decomposition products.  Recent studies have explored the importance of soil carbon stabilization through physical protection and interaction with soil mineral surfaces, with decreased emphasis on stabilization through the mechanism of increasing chemical complexity as organic material decomposes.  Our work focuses on relating soil carbon decomposition and stabilization processes at ecosystem-scales, manifested by the interaction of physical and biochemical controls operating at the level of mineral surfaces and soil aggregates.  Using a mechanistic model based on measurable soil carbon pools derived from a combination of physical and chemical fractionation methods, we explore several concepts relating aggregate formation and mineral/organic carbon interaction to soil carbon stabilization and residence time.