This paper discusses how the "at risk" and "what works" approach that drives the management of youth criminal justice systems produces little knowledge that informs practitioners how best to work with young people who offend and how to design effective crime prevention programmes. An alternative approach that is more informative for the development of effective practices is proposed. This approach prioritises problem-solving and finding out how interventions work. Findings from research we carried out on four local youth inclusion programmes are drawn on to illustrate the potential of this approach to improve practice. (Contains 9 notes.)