Clinical reasoning is a crucial competency for nursing students to develop. In this thesis, we aimed to improve the teaching of clinical reasoning of nursing students in practice for the benefit of patients. To provide a sound knowledge base, we chose the educational design approach, in which objectives, content, teaching and testing must be aligned. The objectives of a clinical reasoning educational programme can be informed by the investigation of the conceptualization of clinical reasoning among experienced nurses. To this end, we compared and contrasted what is written about clinical reasoning of professionals in the medical and nursing literature (Chapter 2). Then, to be able to specify the content of reasoning better, we pursued to gain more understanding about the shaping of experiential knowledge in experienced nurses. We conducted an interview study among expert nurses, followed by directed content analysis (Chapter 3). As a next step, we investigated if and how the development of clinical reasoning can be assessed. We conducted an instrument design study (Chapter 4). And lastly, we studied with a design-based research (DBR) approach if debriefing in a practice setting can contribute to teaching clinical reasoning (Chapter 5). We experienced that even with DBR, which is conducted under the assumption of bridging the theory-practice gap, implementation of an innovation in clinical practice is difficult due to routines and their dynamics. We wrote a perspective paper based on our reflections on DBR and implementation (Chapter 6). The empirical research of this thesis is conducted in the clinical teaching setting of two large university hospitals in the Netherlands. Throughout the thesis we have used the definition of clinical reasoning by Simmons. Clinical reasoning is, “a complex process that uses cognition, metacognition and discipline-specific knowledge to gather and analyse patient information, evaluate its significance, and weigh alternative actions“. Two of our studies build on medical investigations into illness scripts. Illness scripts are organized knowledge structures in long term memory. In these scripts general knowledge of diseases is linked to actual patient care experiences. Illness scripts comprise knowledge components. Originally, three components were identified in physicians: signs and symptoms, fault, and enabling conditions. Illness script theory involves the script as a concept as well as the development of expertise, from novice to expert. In the introduction we referred to the generic didactic model to design education. Based on the research in this thesis, we proposed to enhance the original model with three learning theories. We found that situativity, along with the skills acquisition model and self-regulated learning is the foundation of clinical education development. Our contributions to the development of clinical teaching of nursing reasoning are a deeper understanding of nursing reasoning, nursing illness scripts, a rubric to evaluate, and debriefing procedure and its design principles. Actionable knowledge refers to knowledge for every day practice, based on sound, engaged research and at the same time applicable and relevant to learning and teaching in practice. We view our results as an invitation for more research and continuous improvement in the education of clinical reasoning. Patients and students deserve this actionable knowledge.