Summary: The rise in the number, the diversity, and the needs of disadvantaged preschool-aged children poses a serious challenge to the National Education Goal of readying all children for school by the year 2000. During the 1980s, the number of children who were most likely to face difficulties upon entering school and who would have benefited from preschool programs--poor and at-risk children--increased substantially. Further, the poverty rates for preschool-aged children have increased since the decennial census. Head Start and other preschool programs are now faced with a target population of more poor and at-risk children. Poor children are also more likely than non-poor children to be in at-risk categories. To succeed in school, these children often need special help that may or may not be available, such as language or family support services. In 1990, about one-third of poor preschool-aged children participated in preschool. Only about 35 percent of all poor three- and four-year-olds participated in preschool compared with more than 60 percent of the highest income three- and four-year-olds. Preschool participation rates for poor three- and four-year-olds were consistently low; participation by poor preschool-aged children in rural areas was even rarer.