Over much of the history of Great Britain's Probation Service, its specified mission was to "advise, assist, and befriend" offenders, with little concern about whether or not probation services were reducing probationers' recidivism. Later, belief that the treatment model was ineffective and often unjust, led to the rise of the "nontreatment paradigm," which reframed probation work as a collaboration between the worker and the offender intended to provide help with problems defined by the offender. In youth justice in Great Britain, the main responsibility prior to the reforms following the Crime and Disorder Act 1998 was to ensure the welfare of children and youth who committed delinquent acts. In 1984 the Probation Service was given an official Statement of National Operations and Purpose by the Home Office, marking the beginning of a sustained period of review and reform in which the Probation Service was required to be accountable and provide evidence of its effectiveness. Under this mandate, by 1997 the Probation Service was unable to point to more than a few effective initiatives based on evaluation research. Since that time, however, the Probation Service has developed quality-controlled programs throughout England and Wales in a large-scale enterprise of evidence-based corrections. The book introduced by this chapter contains chapters based on papers that were presented at a colloquium entitled, "Towards Evidence-Based Practice in Probation and Youth Justice," held July 31 to August 1, 2003, at St. Catherine's College, Oxford. The projects discussed are associated with significant changes and developments in probation and youth justice. In this introduction, the editors note that although there is now a rapid accumulation of understanding and knowledge in the probation field, selecting and implementing interventions in a changing social and political environment will challenge and limit evidence-based practice. 37 references