Young people's right to participate in public decision making is increasingly being translated into practice in the UK. A large range of organisations and public bodies are working to involve young people in decisions about policies and practices, from day to day project implementation to long term strategic planning. Among the different types of participation projects this thesis is concerned with those where young people are involved in decision making over a period of time. Despite a number of good practice guidelines, the project literature suggests several seemingly intransigent problems in ongoing youth participation. My aim has been to move forward understandings of ongoing youth participation projects through focusing on a single case study: a group of young people who were involved over a number of years in public decision making within a Scottish local authority. Using a flexible and iterative research methodology, my initial questions on constraints, facilitators and divergence of views amongst stakeholders, were refined over the course of the research. I used a mixture of methods, combining and comparing data from thirty-one interviews, notes from participant observations and project documentation. Carrying out data analysis alongside data collection was a key component of the design. The substantive chapters of this thesis deal with the roles and relationships between young people and participation workers, exchanges between young people and decision makers and accounts of the history of the group. Concepts of representation and decision making between adults and young people receive particular attention. I argue that models and ladders of participation fail to adequately characterise decision making in ongoing participation projects in separating decisions from the relationships in which they are embedded. A central theme running through the chapters is how "being young" is constructed, represented and used. It is my contention that being young is of special salience within youth participation projects. Being young is the basis for involvement; yet what young people are capable of and what they need is not self evident or consistent. Throughout the thesis I examine the ways in which being young is interpreted in different ways in various situations by the project participants. I look not only at the context dependent meanings of being young but also at how these meanings are used as a resource through the life of the project. I conclude by returning to common problems identified in the literature and considering how the findings could contribute to new ways of thinking on these issues.