The National Survey of Early Care and Education (NSECE) team undertook an innovative approach to calculate CCDF program participation. Using probabilistic record linkage methods, the household records from the NSECE were matched to CCDF administrative data from the State of Illinois to form a combined database of survey and administrative data. That combined database allowed creation of CCDF program participation variables from NSECE households' over-time records in the childcare subsidies program. The unified database created from this exercise resembles one from a cross-sectional survey that, by asking retrospective questions, identifies households' recent participation in social programs (CCDF, in our case). But the unified database has the advantage of a more accurate participation variable from administrative data than would have been obtained from a survey self-report. (author abstract)