This study draws together the strands of pupil voice and school improvement, with the aim of investigating some of the underlying causes of underachievement at key stage 3 from a pupil perspective. Recommendations are therefore made about raising achievement in secondary schools which are vulnerable to the failure to reach floor targets (minimum standards for A-C pass rates at GCSE). A sample of staff views were also sought in order to consider similarities and differences in the ways that adults and pupils in the case study school accounted for underachievement and suggested solutions to overcome these barriers. The research uses an action research and case study approach in its design, a focus group method for gathering data and finally, a grounded theory methodology for the analysis of data. It is the use of grounded theory that is central to this study as this leads to a proposed theory of underachievement. The research questions around underachievement are answered and, in addition, a theory of underachievement is constructed from the data. The implications of this theory of underachievement, putting pupil identity and relationships at the centre, is discussed in relation to issues for the DfES, the LEA, the school and for teacher training. In addition, a cycle of underachievement is described and suggestions are made as to how this cycle might be broken. As we move forward towards a climate where "Every Child Matters", the findings here are important in the spirit of putting the young person at the centre and creating a climate of positive outcomes, where the school is the platform on which to build enjoyment and achievement for all our young people.