This report describes and compares the foster care populations of eleven states from the years 1983 to 1998. The authors begin with a profile of the Multistate Foster Care Data Archive, detailing the methodology used to collect the data and explaining the rationale behind administrative databases. The report then examines several issues in foster care. Each state's caseload counts, the number of children in foster care at a specific point in time, are examined. Analysis of the number of children entering foster care follows. Data on this subject are analyzed to better understand foster care processes and who enters foster care. Lengths of spells in foster care significantly affect the foster care caseload; the authors analyze this factor using empirical tools such as event histories. The report's final two chapters examine the exits from foster care spells and the reentry to substitute care. Where the child moves when leaving substitute care varies from reunification with family to other options, such as adoption. However, some of these children eventually reenter the system. Therefore, the authors analyze how placement experiences affect reentry rates.