Aim: To develop a theory that explains the ‘realities’ of part-time nursing. Background: While little is known about the phenomenon of part-time nursing, increasing numbers of nurses work in part-time employment. Methods: Grounded theory. Results: The problem that part-time nurses shared was an inability to achieve their personal optimal nursing potential. Motivators to work part-time, employment hours, speciality, individual and organisational factors formed contextual conditions that led to this problem. Part-time nurses responded to the challenges through a procession of adaptation and adjustment. Conclusion: Harnessing the full productive potential of part-time nurses requires support to limit the difficulties that they encounter. The developed theory provides a valuable guide to managerial action. Implications for nursing practice: Nurse Managers need to consider the developed substantive theory when planning and managing nurse workforces.