Introduction: Illness script theory offers explanations for expert-novice differences in clinical reasoning. However, it has mainly focused on diagnostic (Dx) performance, while patient management (Mx) has been largely ignored. The aim of the present study was to show the role of Mx knowledge in illness script development and how it relates to diagnostic knowledge in the course of development toward expertise. Methods: The participants were 10 fourth-year and 10 sixth-year medical students, and 10 experienced physicians (ie, internists). Participants were asked to study 4 written clinical cases and provide management plans. Based on propositional analysis the management plans were examined for accuracy and elaborateness as well as the number of Mx and Dx items. Results: Providing accurate Mx plans that concurrently pay attention to Dx and Mx was a characteristic of doctors' performance. The Mx plans of sixth-year students were as accurate as fourth-year students, but the format and the size of sixth-year students' plans was more similar to those of doctors. While sixth-year students generated plans with an Mx focus, the plans of fourth-year students were characterized by a Dx focus. Discussion: The experienced physicians' accurate management plans are characterized by a high number of the Mx and Dx items. For sixth-year students the management plans are still incomplete, which leads to generic as well as inaccurate Mx orders. For fourth-year students, the Mx focus is lacking, and hence they seem to treat an Mx task as if it were a Dx task. (Contains 3 tables.)