This article summarizes a report to the California Institute for Energy Efficiency on The Impact of Electric Vehicles on the Southern California Edison System. It begins with a review of previous studies of electric vehicles and their impact on the electric utility. It then describes the assumptions adopted for eight scenarios with large scale use of electric vehicles in southern California. The article then explains the likely impacts of these vehicles on Edison＇s electric loads, its system operation, its total revenue ＇requirements and its average electric rate. The study confirms that electric vehicles can lead to improved load shapes, improved efficiency of operations, and a possible reduction in the average electric rate. But there are unexpected results as well. First, the Edison＇s resource plan could accommodate an unusually large number of electric vehicles if the vehicles are powered by advanced batteries and their charging is subject to smart control. And second, the rate benefits of electric vehicles can be partially erased by an increase in Edison＇s payments to private cogenerators who sell power on marginal cost contracts. The article concludes with an analysis of the reduction in tail pipe emissions if electric vehicles were to displace conventional vehicles in southern California.