As a social endeavour, the practice of nursing is expected to minimise risk of harm to patients. In reality, the risk of breaching or failing to meet a standard of practice, with resultant harm to patients is ever present. Such variations to the expected standard may result in harm to the patient and be viewed as unprofessional conduct within the legislative context. The phenomenon of unprofessional conduct can have significant and sometimes dire outcomes for patients and nurses and provides challenges to understand antecedents to its occurrence and the impact on the nurse. From this realisation, the significance of this study is twofold. Firstly, the literature revealed that an allegation of unprofessional conduct and the associated experience of being reported to a regulatory authority can have significant psycho-social and professional impact on the nurse. Secondly, the phenomenon has received little formal analysis. The purpose of this grounded theory study was to explore the phenomenon of alleged unprofessional conduct, and to develop a theory that provided understanding of the phenomenon and a framework for action. Data was obtained from in-depth interviews of a specialised sample of 21 nurses in any state or territory of Australia who had been the subject of notification by a nursing regulatory authority of alleged unprofessional conduct. Data analysis occurred simultaneously using the constant comparative method. This resulted in the generation of a substantive theory, explaining how nurses dealt with an allegation of unprofessional conduct. This study found that nurses experienced varying degrees and combinations of personal and professional vulnerability. This put them at risk of either making an error, breaching a practice standard, and/or at risk of being reported to a nurse regulatory authority for an allegation of unprofessional conduct. The core social process, a transformation of the personal and professional self is a process that the nurse both 'engages in' and 'goes through', in response to the social problem, being reported to a nurse regulatory authority for alleged unprofessional conduct, and its aftermath. The social process is made up of two categories: loss of the assumptive world: the experience of deconstruction and relearning the world. Loss of the assumptive world is comprised of being confronted, deconstruction of the personal self and deconstruction of the professional self. The category Relearning the world: the experience of reconstruction is constructed of the sub-categories, preserving the self: minimising the unravelling; reconstructing the personal self; reconstructing the professional self; and living within the world. Consequences of the category relearning the world are dynamic and influenced by a number of factors. The ability to transact the deconstructed self and move through the reconstructive processes and experience can be viewed in the following states, stymied, evolving or transacted. The personal and professional transformation of the individual nurse is influenced by the degree of deconstruction initially experienced, the interplay with the influencing factors internal and external support processes; resilience; time; and the constant of vulnerability. The findings of this study have implications for clinical, management, education and research practices in nursing. It also exposes problems with the use of nurse regulatory authorities as a punitive strategy for nurses who err. The uncovering of this substantive theory articulates a process whereby nurses are transformed personally and professionally in response to a traumatic or challenging life event. This substantive theory has value in providing a decision making framework for managing breaches of nursing standards, as a learning tool to identifying and managing risk in nursing and providing a framework for self and external support to nurses who may find themselves in this situation.