This paper presents new estimates of the development of the urban population and the urbanization ratio for the period spanning the Song and late Qing dynasties.Urbanization is viewed,as in much of the economic historical literature on the topic,as an indirect indicator of economic development and structural change.The development of the urban system can therefore tell us a lot about long-term trends in the Chinese economy between 1100 and 1900.During the Song,the level of urbanization was high,also by intational standards-the capital cities of the Song were probably the largest cities in the world.This remained so until the late Ming,but during the Qing there was a downward trend in the level of urbanization from 11％-12％ to 7％ in the late 18th century,a level at which it remained until the early 1900s.In our paper we analysethe role that sociopolitical and economic causes played in this decline,such as the changing character of the Chinese state,the limited impact of overseas trade on the urban system,and the apparent absence of the dynamic economic effects that were characteristic for the European urban system.