This study compared the combined and individual effects of three tillage systems and two cropping systems in a semiarid Mediterranean agroecosystem. The tillage systems were no-till (NT), reduced tillage (RT), and conventional tillage (CT); sites were cropped with either continuous barley or a barley-fallow system. Under both cropping systems, NT treatments had over 30% greater soil organic carbon (SOC) storage in the surface five cm of soil. The continuous barley treatment had greater SOC stabilization than the barley-fallow treatment only under no-till management. NT soils also showed a greater proportion of water stable macroaggregates. The authors conclude that the combined systems of no-till and fallow-suppression have the potential to increase stable SOC in the soil surface as well as improve overall soil structure and aggregation in the semiarid Mediterranean.