The U.S. federal government first introduced incentives for plug-in electric vehicles (PEVs) through the American Clean Energy and Security Act of 2009, which provided a tax credit of up to $7,500 for a new PEV purchase. Soon after, in December 2010, two mass-market PEVs were introduced, the plug-in hybrid electric vehicle (PHEV) Chevrolet Volt and the battery electric vehicle (BEV) Nissan LEAF. Since that time, numerous additional types of PEV incentives have been provided by federal and regional (state or city) government agencies and utility companies. These incentives cover vehicle purchases as well as the purchase and installation of electric vehicle supply equipment (EVSE) through purchase rebates, tax credits, or discounted purchase taxes or registration fees. Additional incentives, such as free high-occupancy vehicle (HOV) lane access and parking benefits, may also be offered to PEV owners. Details about these incentives, such as the extent to which each type is offered by region, can be obtained from the U.S. Department of Energy (DOE) Alternative Fuel Data Center (http://www.afdc.energy.gov/). In addition to these incentives, other policies, such as zero-emission vehicle (ZEV) mandates,1 have also been implemented, and community-scale federal incentives, such as the DOE PEV Readiness Grants, have been awarded throughout the country to improve PEV market penetration. This report reviews 18 studies that analyze the impacts of past or current incentives and policies that were designed to support PEV adoption in the U.S. These studies were selected for review after a comprehensive survey of the literature and discussion with a number of experts in the field. The report summarizes the lessons learned and best practices from the experiences of these incentive programs to date, as well as the challenges they face and barriers that inhibit further market adoption of PEVs. Studies that make projections based on future policy scenarios and those that focus solely on international markets are not included in this report. Studies that only provide an overview of the current market without discussing how incentives influence the market are also not included.