The "lack" or "poverty" of aspirations among young people from disadvantaged backgrounds has become a much discussed topic in UK policy, being regarded as one of the key reasons for stagnating social mobility. While "aspiration" has been the object of previous research, there is no study which adopts a discourse analytic approach to examining the policy debate, its enactment and its negotiation in an educational context. Drawing on the work of Michel Foucault, this thesis examines and compares the discursive constructions underpinning policy debates, school practices and young people's constructions of their futures. The study includes an analysis of policy documents in the UK from 1997-2011 and an in-depth study in a secondary school using interviews, group discussions, observation and documentation. Drawing on frameworks of Foucaultian Discourse Analysis, the data from policy, school and pupils were first analysed separately and then examined for convergences and divergences. The analysis identified that the discourse of "aspiration" in policy and among teachers was conveyed to the pupils though a discourse on "success" promoting Higher Education and highly-skilled occupations, as well as attitudes and behaviours which allow realising these aims. Among the young people, some pupils aligned themselves fully with the discourse of success, while others negotiated the demand to "aim high" with their perception of lacking innate ability.