In the Netherlands, most building takes place on land supplied by the municipality, and this has been the case for the last 40 years or so. This is an almost unique situation in the Western world, and it is even more remarkable considering that the Netherlands has a thriving and dominant market economy. Moreover, for very many years most of the private parties involved in building development - owners of development land, property developers, building contractors - were happy with this situation and wanted it to continue (but increasingly they are challenging it: recent changes are described later). Most non-Ditch find this very puzzling: the aim of this article is to describe Dutch land policy and to explain the puzzle. First, the land policy is explained in the terms which the Dutch are accustomed to use for it. Then that policy is analyzed using conventional land-price theory. Finally, some very recent changes are described and explained using the analysis.