Data from the 1997 National Survey of America's Families (NSAF) are analyzed to estimate the number and composition of children lacking health insurance prior to the implementation of the State Children's Health Insurance Program (CHIP). The NSAF is a survey of children and adults under the age of 65 in more than 44,000 households, conducted as part of the Urban Institute's Assessing the New Federalism project. Overall, information was collected on 34,439 children. Findings indicate that 9.2 million children aged 18 and under lacked insurance coverage in 1997. Over three-quarters of these children were in families with incomes below 200% of the federal poverty level. Another 14% were in families with income between 200 and 300% of the federal poverty level. Older children were more likely than younger children to be uninsured. Almost half of all low-income individuals aged 19 and 20 were uninsured (47.7%). With CHIP, states have the potential to provide insurance coverage for almost all low-income uninsured children aged 18 and under. The challenge will be to translate that potential into coverage for all eligible but uninsured children. (Contains 3 tables and 20 references.) (SLD)