The Committee on Authentication Technologies and Their Privacy Implications of the National Research Council was established by the Computer Science and Telecommunications Board (CSTB) to examine the interaction of authentication and privacy. The committee sought to identify the range of circumstances and the variety of environments in which greater or lesser degrees of identification are needed in order to carry out governmental or commercial functions. It also addressed ways in which law and policy can come to grips with the flaws that are likely in the technology or its implementation. It considered how the federal government can deploy improved authentication technologies consistent with the desire to protect privacy. It also examined the broad implications of alternative approaches to selecting and implementing authentication technologies by the federal government and others interested in their use.