Researchers have the responsibility not to pander to politicians’ and bureaucrats’ demands for certainty, for a single right answer. The claims they make for evaluative research should in one sense be more modest, since they will not be concerned with ultimate truths. However, in another sense, their claims can be more confident, if they avoid the positivist trap of believing that only the most scientific approaches can tell politicians and bureaucrats anything useful. It is unrealistic to expect that youth justice policy, or criminal justice policy in general, will be shaped by research, but it is reasonable to expect that research will be one of the factors that influence and inform it. In this chapter, the author reflects upon evaluative research and the positivist conceptions that inform “what works” models and the possibilities of applying evidence to policy formation are considered. References