A key objective of public schooling in the Danish social democratic welfare is to generate equal opportunities for all children regardless of family background and resources. But is public schooling in Denmark a “social equalizer” and to what extent are the initial differences between children reduced when they are facing the transition into adulthood? Using data from the Danish Longitudinal Survey of Children, this study investigates the role of the cognitive, social and emotional development throughout the preschool years (age 7 to 15) with regard to four central markers important for a successful transition to adulthood: health outcomes, continued education, labour force participation, and non-involvement in criminal behaviour.