Three rounds of in-depth studies have been undertaken in the second year of each information-gathering cycle. The first was a comparative study of population and development of two port cities in each of five countries. The second was a study of population dynamics and urban infrastructure in eight cities. The third dealt with specific problems of migration and family planning services in three cities. All three reinforced and deepened some of the findings of the Inquiries and also provided some unexpected results, which could be turned readily into implications for policy and research. Below we describe the organization and coverage of each of the studies, make observations from them, and finally identify the lessons to be learned from them..