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. Sense-Making, a qualitative research method, was utilized to obtain and analyse data from interviews with 10 registered nurses in order to study reflective thinking in actual nursing practice. Ten non-routine nursing situations were analysed for the presence of reflective thinking. Time-line interviews of the events resulted in a total of 59 micro-moments, each of which was explored in terms of the thinking processes utilized to make sense of the situation as well as the focus of their thought. 'Pre-perceptions' played an important part in how the respondents perceived their situation. Reflective thinking was extensively manifest, especially in moments of doubt and perplexity, and consisted of such cognitive activities as comparing and contrasting phenomena, recognizing patterns, categorizing perceptions, framing, and self-questioning in order to create meaning and understanding. Self-questioning was identified as a significant process within reflective thinking. By exploring and analysing the type of questions respondents were asking themselves, the study uncovered three hierarchical levels of reflective thinking. Respondents 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 realization of multiple perceptions and multiple responses. Reflective thinking-for-critical-inquiry could not be demonstrated in the study sample. The findings of this study resulted in the development of a model of reflective thinking, which is discussed in terms of the implications for learning in nursing practice.