Expertise is marked by outstanding performance of a person in a specific area or profession. In many professions, the level of expertise is also reflected in his or her professional vision. That is, a person’s ability to detect relevant elements in the environment and interpret them appropriately to guide his or her actions on a task (Goodwin, Am Anthropol 96(3):606–633. https://doi.org/10.1525/aa.1994.96.3.02a00100, 1994). This is in particular true for professions with a high visual component, such as medicine, air traffic control, car driving, or teaching. Eye tracking, a method to objectively measure where a person looked at, for how long, and in which order, is a well-established method to investigate this aspect of expertise. Also, eye movements often reveal information that cannot be accessed consciously by agents and are therefore of high relevance for understanding the development of expertise. Findings from empirical research show that experts’ eye movements are more knowledge-driven whereas novices are more image-driven, that means that novices’ visual attention is more often attracted by salient misbehaviors. This book chapter will highlight applied contributions of eye tracking research to expertise development in the domain of teaching. As research in this specific domain is still scarce, we will transfer findings from other domains into teaching and introduce it as the new promising area where gaze behavior plays a crucial role. Finally, we will discuss the potentials of professional vision and eye tracking for trainings in the acquisition of expertise.