This thesis provides a reflexive critique of the power structures which constrain nursing actions in the practice setting, an abortion clinic, of the registered nurses who participated in this study. The development of abortion services, like other health services for women, has been based on a medical ideology of health which has created many ethical dilemmas for nurses. One of the most complex of these is the extent to which nurses should fulfill the role of client advocate. While the literature on nursing advocacy has been prolific, published research in this area is scant. The theoretical assumptions of critical social science, provide the basis for the methodological approach of action research adopted in this study. In depth, unstructured interviews involving exchange of dialogue amongst the participants with the researcher focused on the participants' experiences of their own nursing practice, with a view to uncovering and removing constraints, which had prevented them fulfilling an advocacy role. Diaries were also kept and used as supplementary research tools. The analysis of the data demonstrates the ways in which nurses interpret their own practice world as a system independent of their own actions. It shows how the shared understandings of the participants were 'ideologically frozen' and power relations inherent in the health care system are deep rooted and subtle, coming to be treated as natural by the nurses, and so denying them their own ability to make changes. It is suggested that opportunities for nurses coming together and engaging in such critically reflexive dialogue may provide a basis for future emancipation from traditional power structures. In this way effective and satisfying nursing practice dependent on emancipatory knowledge and a reinterpretation of power structures may result in an advocacy role for nurses.