In most European countries a ‘childcare gap’ exists: that is, a discrepancy between the demand for and provision of childcare. Among the countries that are succeeding in closing the gap are the Nordic welfare states. Hence, knowledge about how childcare provision in these countries has developed is of wide interest. This article stresses the importance of studying how the interactive processes of changing provision and demand explain the building up and the closing of national childcare gaps. Although there are similarities in the development of Nordic childcare services, some differences stand out. The comparison indicates that complex societal processes interact in shaping provision and demand. These dynamics are explored in more detail in the Norwegian case, where the interactive processes have produced an ever-increasing demand for childcare. The demand side is crucial, particularly the role of mothers in generating momentum for policy change. Mothers' changing labour market patterns and their demand for childcare are important driving forces for policy change.