As a product of the Early Childhood Subcommittee of the National Education Statistics Agenda Committee of the National Forum on Education Statistics, this report evaluates the types of data needed to assess the status of children in their preschool years, evaluate the impact of their early experiences, and address policy questions related to early childhood care, education, and school readiness. It is published as an addendum to "A Guide to Improving the National Education Data System." Issues that must be considered in studies of child development include learning and developmental stages, well-being, child care, education, and the concept of readiness. Associated data collection issues are those of definition and measurement, data needs, and possible indicators for an early childhood database. Recommendations include: (1) giving high priority to developing basic indicators; (2) developing and implementing methods to assess developmental progress; (3) developing and implementing a survey of early childhood care and education programs; (4) linking developmental assessment and the survey data; and (5) undertaking longitudinal studies to assess factors affecting child well-being. An appendix lists specific examples of possible indicators for an early childhood database. (SLD)