Expertise in foreign language teaching has been widely discussed in the literature as inherently related to accumulated classroom experience and, hence, extensive practical knowledge. Even though current conceptualizations are increasingly focusing on teachers’ ability to reflect on their performance and continuously develop a repertoire of didactic resources regardless of their career stage, effective human information processing in the profession remains under-researched. This paper sees the concept of expertise from the perspective of cognitive processes, and specifically operations involved in problem-solving. The author presents a theoretical model of teacher fossilization, discussing attention, knowledge, reasoning, and judgment as potential inhibitors of intellectual vitality and growth in individuals. When neglected, these factors might lead experienced teachers to make just as incompetent decisions as novice educators. The model highlights the external and internal forces that cause practitioners to minimize, rather than maximize, their learning opportunities in a workplace. The new concept has implications for teachers’ day-to-day practice as well as for in-service professional development initiatives. It serves as a guiding principle for the successful utilization of one’s cognitive capital and outlines both the purpose and direction of one’s mental effort.