The concept of systematic reviewing of research literatures became influential in the second half of the 20th century, in the context of the longstanding, and challenging, issue of how to 'translate' research findings into reliable guidance for practical decision-making-to determine which policies, programs, and strategies should (and should not) be adopted (Hammersley 2014;Nisbet and Broadfoot 1980). The idea that research can make a significant contribution in assessing the effectiveness of policies and practices was hardly new, but it was greatly bolstered around this time by the emergence of the evidence-based medicine movement. This identified a problem with the effectiveness of many medical treatments: it was argued that research showed that some commonly used ones were ineffective, or even damaging, and that the value of a great many had never been scientifically tested; despite the fact that such testing, in the rigorous form of Randomised Controlled Trials (RCTs), was feasible. Subsequently, the idea that practice must be based on research evidence about effectiveness spread from medicine to other areas, including education.In some countries, notably the UK, this coincided with increasing political criticism of the education system for failing to produce the levels of educational achievement required by the 'knowledge economy' and by 'international competition'. Such criticism was closely related to the rise of the 'new public management' in the 1980s, which focused on increasing the 'accountability' of