This monograph examines the theoretical and practical significance of experts, consultants, and advisors in contemporary society. Clearly, there is a growing layer of knowledge-based professions that has led to the pluralization of expertise and the multiplication of experts. Decision-makers in organizations, as well as private citizens, are increasingly seeking the advice of experts. The two authors analyze important aspects of expert activity and argue that the role of experts must be distinguished from that of other professions, scientists, or intellectuals. Experts engage in knowledge-based activities that mediate between the context of knowledge production and knowledge application.