A broad definition of technology is any modification of the natural world made to fulfill human needs or desires. From computers and genetically modified foods to superhighways and satellites, technology pervades our lives. To be an informed citizen requires understanding the nature of technology--how it is created, how it shapes society, and how people influence its development. In other words, informed citizens must be technologically literate. Nevertheless, very little has been done to determine the level of technological literacy in the United States. This important report describes and evaluates methods and opportunities for assessing technological literacy in K–12 students, K–12 teachers, and out-of-school adults. The report suggests how scientifically valid, broadly applicable assessments might be developed for the three target populations. Findings and related recommendations are provided in five critical areas: instrument development, research on learning, computer-based assessment methods, framework development, and public perceptions of technology.