Understanding of human expertise and its acquisition has progressed substantially since Chase and Simon’s seminal studies of chess expertise. Computational theories of expertise have been developed in domains such as memory, mental calculation, chess, and problem solving that explain expert performance at the level of cognitive structures and processes. Basic and use-inspired studies have demonstrated the generative property of cognitive models of expert skill. The latter show the value of such models for solving practical, high-stakes problems, e.g., landmine detection. The fundamentally adaptive nature of human expertise makes expert models valuable resources for understanding intelligence and engineering solutions to difficult problems.