The purpose of this article is to introduce and consider some of the issues which may arise in research projects seeking to engage young people as co-researchers. The article will focus on the methodological challenges faced by one research team in particular, in the design and implementation of a lottery funded project in England which is intended both to improve understanding of young people's health needs, and to develop better strategies for meeting these. In developing the project design, the research team judged that a collaborative approach would be appropriate given the subject matter and the intended outcomes of the research. In order to achieve this, considerable thought was given to the implications of recruiting a team of young people to act as 'co-researchers.' As a result, a number of significant methodological issues were identified, grouped around several key themes:-practicalities;ethics; validity; and value. The article develops these questions further, identifying a number of challenges in each area, and exploring the possible consequences for research projects which involve young people as co-researchers. Based on these observations, the article goes on to discuss some of the strategies adopted by the research team carrying out the study in question, in order toaddress the methodological and ethical concerns identified. The article concludes that there are very real benefits to be gained by adopting participatory research methods, which clearly offset the additional demands involved in pursuing this kind of approach.Key words: Participatory research, young people, methodological issues, insider perspective C:\Documents and Settings\acope\Local Settings\Temporary Internet Files\Content.Outlook\BH1RCOLE\Children and Young People as Co-researchers.docThe context: young people's health needs and participatory researchThe issue of young people and social exclusion has recently become a subject of significant interest in England and the rest of the United Kingdom. As a consequence, there have been increasing demands for a better understanding of young people's needs, particularly those of young people who have been marginalized for one reason or another. In order to respond to this interest, De Montfort University and The Children's Society developed a joint proposal to research the health needs of socially excluded young people in 1998. This proposal was informed by a strong belief that young people's own views should be incorporated as far as possible, and that the subjective aspects of their needs should be properly identified (Broad, 1999). This, it was felt, would offer certain benefits in adding to the richness, validity and relevance of the research project itself (see, for example, Wilkins, 2000). It has also been argued that participatory research is beneficial both because of its implicit values (such as empowerment and inclusion), and also because it improves our level of understanding of the substantive subject area (see, for example, Lewis and Lindsay, 2000).The detailed rese...