Background: the training requirements leading to the state nursing diploma places learning about clinical reasoning at the center of the training. We have been wondering about the possibilities of making visible the student nurse’s mental processes when they provide nursing care in order to identify their strategies and reasoning difficulties. It turns out that concept mapping is a research tool capable of showing these two aspects. Objectives: the aim of this study is to see whether a concept map made during an interview and created from the speech of a nursing student when analyzing a simulated clinical situation, is able to make visible his/her strategies of clinical reasoning and reasoning difficulties. In a second phase, we explore how, once created, the concept map allows students to identify their own intellectual reasoning. Method: Twelve second year nursing students participated in the study. Concept maps were constructed by the trainer/researcher as the students analyzed aloud a simulated clinical situation written. Concept maps were analyzed from a reference grid. Interviews were conducted following the creation of concept maps and student’s comments were analyzed. Results: students’ reasoning strategies were either mixed inductive dominant (5/12) or hypothetical-deductive dominant (5/12). Reasoning difficulties identified were related to the lack of identification of important information, the lack of analysis of data, lack of connection or the existence of faulty links. Analysis of the comments highlights that concept mapping contributed to the development of metacognitive skills. Conclusion: concept mapping has been shown to have benefits in contributing to a diagnostic assessment of clinical reasoning learning. It is an additional resource tool to facilitate the development of metacognitive skills for students. This tool can be useful in implementing learning support strategies in clinical reasoning.