The study of expertise is important for society in several ways. First, it sheds important light on learning and the acquisition of knowledge, which can be used to develop better methods of instruction and training. Given the pace at which technology advances in our society, this is a significant contribution. For example, research on physics and mathematics expertise, together with other studies, has led to the development of artificial tutoring systems in mathematics that perform better than human teachers. Second, research on expertise can lead to better ways of coaching experts. The clearest illustration of this comes perhaps from sport and music. In athletics, world records are improved every year due to better training techniques, and the difference between current and previous achievements is sometimes stunning. The winners of Olympic medals in the marathon one century ago recorded times similar to today’s amateur runners. In swimming, the seven world records that earned Mark Spitz as many gold medals at the Munich Olympic Games in 1972 would not have been sufficient for qualification for the semi-finals in the 2008 Beijing Olympic Games. Third, research on human expertise can inform the development of artificial expert systems performing at high or even human-like levels. Expert systems are much cheaper, do not tire, and do not move to other jobs – considerable advantages from the point of view of industry. Thus, expert systems can make valuable contributions to the economy.