Agencies that serve the needs of children must accommodate occasional abrupt changes in the size of their target populations. Over the last 30 years, school districts have had to adjust quickly as the numbers of students have surged, receded, and surged again. This Brief shows the latest changes in the numbers of preschool-age (under 5 years) and school-age (5 through 17 years) children for each State. The estimates cover the period from the 1980 census to July 1, 1986, and are computed from decennial census data, from birth and death records, and from information collected for administrative purposes such as school enrollment, income tax, and housing records.