The dawn of the twentieth century witnessed a significant development in Indonesian social history in that urban centers replaced the role of rural communities as the loci of change. As much as the colonial demand of land and labour in the nineteenth century had changed the structure of the countryside, the development of commerce and industry inthe twentieth century resulted in the reconstruction of the social life in the centers of those activities Urban population, especially in the large cities of over 100,000, increased rapidly. Basing himself on the 1930 census data, Wertheim noted that in 1930 8 51 percent of the population of Java and Madura lived in 102 urban centers. In the course of a decade from 1920 to 1930 urban population percentage to the total population had increased 1 percent Only in East Java was the development less impressive. There the cities of 25,000 to 50,000 were stagnating, and there was sharp relative and absolute regression in the cities with a 10,000 to 25,000 population. What is more important, according to Wertheim, is the ‘mental climate’ of the urban centers that signified a new era in history