Knowledge-based systems are a new type of advice-giving computer program with an increasing range of applications in many of the major institutions in our society. They are now being used by commercial, financial and manufacturing companies, welfare, educational and legal services, policy-making bodies and the military. This report aims to alert the public to the potential benefits and possible dangers of advanced information technology. It provides a survey of the applications and social implications of knowledge-based systems and makes recommendations for professionalism in future development and marketing.