In many domains of the study of education and human development the number of empirical studies is large but replicable reviews and critical analyses of this literature are almost absent. The use of empirical data for the development of theory or for practical goals and for policy purposes is therefore less than optimal. Because we strive for evidence-based implications of research for practice, it is our intention to conduct meta-analyses in every domain of empirical study that is or will be covered in the current research programme. Not only policy and practice but also research and theory may profit from this approach, as new and evidence-based hypotheses emerge from the meta-analytic synthesis of past research endeavours.