As noted, we use administrative data from the welfare, Medicaid, and child welfare agencies in three states. Because we were using existing databases, it was imperative that we achieved common definitions and standardized data elements across the three states. We achieved that through close collaboration with researcher groups in each state that are most familiar with the information systems. The individual-level AFDC, Medicaid, and foster care records were linked by child in order to develop "spells" that corresponded to the transitions of interest. A diagram of the database structure for each state illustrates how the databases were constructed.