The Bonneville Power Administration operated a Residential Weatherization Pilot Program from 1980 through 1982. The program provided free home energy audits to 7200 electrically heated homes in the Pacific Northwest and gave zero-interest loans to weatherize 4100 of these homes. The total cost of the program was almost $11 million. The pilot program and its regionwide successor are intended to provide benefits to the Pacific Northwest region for roughly 30 years in terms of reduced residential energy consumption. Therefore, it is important to determine the durability of the electricity savings due to the program. Estimates of long-term savings affect power supply planning in the region and influence the economics of the program itself (i.e., the level of funding that BPA can justify for the program). This article presents empirical results concerning the total and net energy-saving affects of the BPA pilot program 1, 2, and 3 years after participation. The total annual electricity saving experienced by households that received an energy audit and a weatherization loan averaged 5300 kWh 1 year after participation, increasing to 6000 and 6500 kWh 2 and 3 years after participation, respectively. The net annual electricity saving that can be directly attributed to the program for these audit plus loan households averaged 4500 kWh (15% of preprogram use) 1 year after participation and declined slightly to about 4300 kWh 2 years and 4200 kWh 3 years after participation. The article uses these empirical findings with a simple simulation model to estimate the effects of the program into the future. Assuming that electricity prices remain constant after 1984, total energy savings increase to a level of 7000 kWh, while net energy savings decrease to 3600 kWh for the audit plus loan households. Alternative electricity price scenarios are discussed.