The first National Education Goal agreed to be President Bush and the nation's governors is that all children will start school ready to learn. The first objective under that goal is that of providing high quality and developmentally appropriate preschool programs for all disadvantaged and disabled children. This paper seeks to assist efforts to achieve that objective by defining key concepts and providing background information concerning the size of the target population, levels of preschool participation by disadvantaged and disabled children, and indicators of the quality of the programs in which disadvantaged and disabled children are enrolled. Enrollment patterns are described in terms of the preschool participation of disadvantaged children, private versus public programs, trends in enrollment by income across time, differences by race and Hispanic origin, preprimary enrollment levels among Hispanic children, Head Start, prekindergarten programs supported by Chapter 1 funds, and state-funded prekindergarten programs. Data indicate that about half of the 4-year-olds in poor families nationwide receive preschool instruction, either from Head Start, Chapter 1, or state-funded programs. The same is true for less than 20 percent of poor 3-year-olds. By 5 years of age, nearly all children from low-income families are enrolled in public school kindergarten or prekindergarten programs. An appendix describes the kind of data system that would be desirable for the monitoring of progress toward the objective of providing high quality programs to all disadvantaged children. (56 references) (RH)