This report summarizes available scientific information establishing the crucial role that Southern Orange County could play in efforts to conserve biodiversity at both global and regional scales. The report outlines a conservation framework for the area, using principles of conservation planning to delineate four core biological resource units. These four resource units must be conserved essentially intact, without further internal fragmentation by development, to continue supporting key species and ecosystem processes. We present this information in support of the Natural Community Conservation Planning (NCCP) program for the Sotuhern Oregon County NCCP subregion.