Conventional pavements rely on stiff upper layers to spread traffic loads onto less rigid lower layers. In contrast, an inverted pavement system consists of an unbound aggregate base compacted on top of a stiff cement-treated base and covered by a relatively thin asphalt concrete layer. The unbound aggregate interlayer in an inverted pavement experiences high cyclic stresses that incite its inherently nonlinear granular media behavior. A physically sound, nonlinear elastoplastic material model is selected to capture the unbound granular base in a finite-element simulator developed to analyze the performance of inverted pavement structures. The simulation results show that an inverted pavement can deliver superior rutting resistance, as compared with a conventional flexible pavement structure with similar fatigue life.