This paper examines the ways in which the North American experience has influenced youth mentoring programmes in the UK and focuses on the theoretical assumptions about young people which have underpinned mentoring interventions. A more critical approach to this North American 'legacy' is required if the value of this form of intervention is to be accurately assessed. The paper argues that an over-reliance by mentoring interventions on developmental paradigms has curtailed their capacity to take account of the wider social context in which young people are making their transitions to adulthood. It is suggested that alternative theoretical frameworks which address the complexity and multiplicity of youth transitions hold more promise for understanding and theorising the role of mentoring in the UK setting. A recent Scottish study of informal mentoring processes attempted to open up these theoretical possibilities by using a framework which recognised young people as active participants and agents. This study revealed that a range of models of mentoring may be in place within informal mentoring relationships. The paper argues that findings from this study demonstrated a need for a more critical approach to the 'classic notion' of mentoring as exclusively a one to one relationship between an adult and a young person. Since mentoring is now a highly popular form of intervention with 'socially excluded' young people these questions about the theoretical base for the concept require urgent attention.