For several decades, the city of Copenhagen has been using a simple centralized daycare assignment mechanism, offering parents the freedom to choose from over 300 public daycare centers across the city. The purpose of this study is to identify and document some of the key challenges associated with the Copenhagen daycare assignment system, utilizing survey evidence, administrative data from the daycare authority, and register data. Understanding how the Copenhagen system tackles these significant challenges will provide valuable insights for enhancing daycare assignment mechanisms on a broader scale. By studying and addressing these issues, we can work towards creating more efficient and effective daycare assignment processes for parents and children in various settings.