This thesis explores how respiratory nursing expanded its scope of practice at a professional level and at an individual practitioner level in recent years. The introduction of the respiratory Clinical Nurse Specialists (CNSs) and Advanced Nursing Practitioners (ANPs) roles are among the most significant changes in recent years. The timing of this study is significant as the first wave of Covid-19 had just occurred as this research was conducted. Hence, it provides insight into the experiences of a group of respiratory nurse specialists in Ireland as they responded to the first wave of a global pandemic. Respiratory CNS/ANPs are responsible for educating their colleagues and patients under their scope of practice, significantly expanding their role to include activities which were formerly the remit of medical colleagues. While the expanded role benefits patients and consultants, it also raises issues concerning professional identity formation and education. This research explores how respiratory nurse specialists (CNS/ANP) enhance practice development, generate knowledge-based practice, and contribute to learning, education, and research in the sector. This qualitative study consists of qualitative online interviews with 15 respiratory CNSs/ANPs about their experiences as respiratory nurses during the first wave of Covid-19. The study is based on a hermeneutic phenomenological approach. Findings reveal that the respiratory CNS/ANP role enhances and complements nursing practice on an individual and sectoral level, enabling a more agentic practitioner professional identity and education for colleagues and patients. The expanded role raises key issues for professionalism and multidisciplinary teamwork in nursing and nurse education, the positioning of advanced practitioner roles in changing healthcare hierarchies, and the nature of education and knowledge formation in practitioner-based professions. These findings can inform those with responsibility for regulating respiratory CNS/ANP nursing practice and those responsible for education and research in the nurse context, especially in the context of global changes due to Covid-19.