This report summarizes progress throughout the nation in establishing voluntary programs linking home energy rating systems (HERS) and energy-efficient mortgages (EEMs). These programs use methods for rating the energy efficiency of new and existing homes and predicting energy cost savings so lenders can factor in energy cost savings when underwriting mortgages. The programs also encourage lenders to finance cost-effective energy-efficiency improvements to existing homes with low-interest mortgages or other instruments. The money saved on utility bills over the long term can more than offset the cost of such energy-efficiency improvements. The National Collaborative on HERS and EEMs recommended that this report be prepared.