Literature, including service users' own accounts, confirms that people labelled as `mentally ill' experience oppression and powerlessness both in their contacts with psychiatric services and more widely in society. There are calls to challenge this oppression by engaging in strategies for empowerment, for example via advocacy and campaigning by the mental health user/survivor movement. Research has also been identified as a strategy for empowerment for mental health service users. This dissertation proposes participatory research (PR) as a potentially empowering research methodology consisting of a process of investigation, education and action in which participants work jointly with researchers throughout. This research therefore aims to: explore the nature of oppression and power in the lives of mental health service users in Britain; assess the extent to which participatory research can function as a strategy for empowerment for mental health service users; consider the extent to which PR principles can be adhered to in research with mental health service users; and highlight issues for methodological development arising from the practice of PR. These aims were explored via a year-long PR project in which the author worked jointly with a group of mental health service users to design and undertake research, and to take action based on its findings. Fieldwork data are analysed in the context of existing theoretical, conceptual and empirical literature on oppression, power, empowerment and PR. It is concluded that PR can facilitate processes of individual and group empowerment for mental health service users, and may therefore be a first step towards the longer-term goal of achieving empowerment in the liberational sense of changing oppressive social structures. This latter goal is more likely to be achieved by combining research with other strategies for empowerment such as collective action and campaigning, and by joining together with other oppressed groups with common interests, such as the disability movement.