In many societies today, there has been an increase in out-of-school time education, extended education, for children and adolescents. Extended education is a field that has been growing rapidly in recent years. This issue provides an overview of developments in various countries around the world. Theoretical considerations on similarities and differences between the processes are combined with empirical data. Extended Education as an umbrella term is discussed. The contributions show (1) an overview over the field, (2) different forms of institutionalization, learning outcomes, effects on the reduction of social inequality and social risks in growing up and on the well-being of children (country case studies) and (3) comparison between different countries in its development.