This article describes collaboration between system dynamicists and economists to model a multi-sector, ecological-economic model of population and resource dynamics that is firmly based on economic theory and leverages the strengths of both fields. This model illuminates how an SD approach allows model complexity to be extended in order to effectively model interactions between an economic system and an ecological system. Specifically, the simulation exercise demonstrates how SD model analysis can help explain the counterintuitive model behaviors due to increases in the natural resource carrying capacity or regeneration rate. The simulation results also reveal that allowing for out-of-equilibrium states (adaptation) significantly impacts the dynamics of ecological economic systems, a point often neglected in the economics literature. These findings, while familiar to system dynamicists, highlight the potential for SD to contribute to other disciplines, including economics.