For the past hundred years, innovation within the automotive sector has created safer, cleaner, and more affordable vehicles, but progress has been incremental. The industry now appears close to substantial change, engendered by autonomous, or "self-driving," vehicle technologies. This technology offers the possibility of significant benefits to social welfare — saving lives; reducing crashes, congestion, fuel consumption, and pollution; increasing mobility for the disabled; and ultimately improving land use. This report is intended as a guide for state and federal policymakers on the many issues that this technology raises. After surveying the advantages and disadvantages of the technology, RAND researchers determined that the benefits of the technology likely outweigh the disadvantages. However, many of the benefits will accrue to parties other than the technology's purchasers. These positive externalities may justify some form of subsidy. The report also explores policy issues, communications, regulation and standards, and liability issues raised by the technology; and concludes with some tentative guidance for policymakers, guided largely by the principle that the technology should be allowed and perhaps encouraged when it is superior to an average human driver.