While it is claimed in the nursing literature that reflective thinking is the approach par excellence for learning and advancing the art and practice of nursing, few empirical studies have been undertaken in this area to date. This thesis presents a study of reflective thinking. Sense-Making, a qualitative research method, was utilised to obtain and analyse data from interviews from ten Registered Nurses. After exploring the seminal works of Dewey and Schön, the concept of reflective thinking was clarified in order to arrive at an operational definition. Ten non-routine nursing situations were analysed for the presence of reflective thinking Time-Line interviews of the ten events resulted in a total of 59 Micro-Moments, each of which was explored in terms of how nurses engaged in reflective thinking, and furthermore, what the focus of this reflective thought was. Reflective thinking was extensively manifest, especially in moments of doubt and perplexity. 'Pre-perceptions' played an important part in how the participants perceived their situation. Reflective thinking, an active cognitive process to create meaning and understanding, consisted of such activities as comparing and contrasting phenomena, recognising patterns, categorising perceptions, framing, and self-questioning. The latter activity was identified as a significant process within reflective thinking. By exploring and analysing the type of questions participants were asking themselves, the study uncovered three hierarchical levels of reflective thinking. Participants most often engaged in reflective thinking-for-action which centred on the here and now in order to act. Reflective thinking-for-evaluation focused on creating wholeness and contributed to the realisation of multiple perceptions and multiple responses. Reflective thinking-for-critical-inquiry is the highest level of the 'Reflective Thinking Pyramid' even though its occurrence could not be demonstrated in the study sample. The findings of this study resulted in the development of a 'Dynamic Process Model of Reflective Thinking', and are discussed in terms of the implications for nursing practice and nursing education. Finally, the Sense-Making Method is recommended as a framework to encourage and guide reflective thinking in nursing practice.