This book derives from the author's thesis submited in partial fulfilments of the University of the West of England, Bristol for the degree of Doctor of Philosophy. It develops and applies a rational decision-making model to the youth justice process up to, and including, the sentencing stage. In principle this model is, and should be, universal and suitable for analysing and assessing the rationality of sentencing (in terms of available information necessary for rational decision-making) in different jurisdictions with different procedural traditions. By applying the model to youth sentencing in Vietnam and in England and Wales, this book identifies problems in each. Given that both Vietnam and England and Wales require a rational youth sentencing process in order to fulfil their international obligations, the book identifies the pre-sentence report in England and Wales as an appropriate tool for providing sentencers with the information necessary for rational sentencing, and argues that suitably adapted it may assist Vietnam in complying with its international obligations.