The focus of this research is authenticity in leadership in middle managers viewed through the perspective of the middle manager using a critical realist research design approach. The aim of the study is to critically assess the importance of authenticity in leadership to middle managers and to investigate the expectations middle managers have around authenticity in the workplace. Whilst there are areas of research into authenticity in senior leaders and the role of the middle manager, this study argues that there is a dearth of evidence of research into leading with authenticity in middle managers, specifically the tensions and opportunities of leading authentically. This thesis aims to contribute to research literature in this area. There is a lack of empirical research into the lived experience of middle managers, which this research begins to address with a view to developing a broader understanding of authenticity in leadership in middle managers. This thesis addresses the question ‘What factors shape authenticity in leadership in middle managers?’ A purposive sample of confidential interviews analysed using thematic coding and a critical realist research design addresses the thesis aim. This qualitative exploratory study was undertaken in East Lancashire, UK with ten Master of Business Administration (MBA) apprentices. The apprentices work alongside their study as middle managers within organisations of varying size. The participants provide an account of their lived experience of authenticity in leadership in their role and how important it is to them. The key findings of the study are that the middle managers valued authenticity in their leadership as middle managers and felt that they were able to lead with authenticity in most situations in the workplace, with the exception of two scenarios. Firstly, they felt that they were less authentic when liaising with the senior management team as they did not want to be perceived negatively in a way that may expose their lack of knowledge or experience and potentially threaten their career progression. Secondly, they behaved less authentically if they did not know the person with whom they were working very well and had not engendered trust in that person. Many implications for practice arise from this study including the way in which organisations may be able to implement training for different groups of employees - the middle managers themselves, their superiors and their subordinates - to provide learning of how authenticity could be used to develop trust and build relationships so that colleagues could work together more effectively. Limitations of the research are considered, and areas of future research identified.