This report systematically reviews research on the outcomes of programmes that teach young children in a group setting before they begin reception. Study inclusion criteria included use of randomised or matched control groups, evidence of initial equality, and study duration of at least 12 weeks. Studies included valid measures of language, literacy, phonological awareness, mathematical, and/or cognitive outcomes that were independent of the experimental treatments. A total of 38 studies evaluating 27 different programmes met these criteria for outcomes assessed at the end of preschool and/or reception/kindergarten. The review concludes that on academic outcome s at the end of preschool and/or reception, 6 early childhood programmes showed strong evidence of effectiveness and 5 had moderate evidence of effectiveness. Of the 27 programmes reviewed, 7 are available for implementation in the UK. A few longitudinal studies have followed their subjects into secondary school, and even adulthood. These studies show that comprehensive programmes focused broadly on cognitive development rather than solely academic skills had better long-term effects on social adjustment outcomes such as reductions in delinquency, welfare dependency, and teenage pregnancy, and increases in educational and employment levels. (author abstract)