This report provides information on factors that are associated with children's progress through elementary school and high school. Children's rates of advancement through school were measured by comparing the grade attended in 1976 with the typical grades attended by children at each age. The grade in which most children of a given age were enrolled was called the modal grade. Children's relative progress through school was measured by whether they were at or below the modal grades for their age. The factors related to school progression investigated in this report were sex, race, Spanish origin, language ability, region of residence, metropolitan-nonmetropolitan residence, poverty status, and educational level of family head. Analysis of survey data showed a decline between 1950 and 1976 in the proportion of persons five to 17 years old who were below the modal grades for their age. When compared with the total population, significantly higher proportions enrolled below the modal grade were found for youth who were black or of Spanish origin and living (1) in families maintained by an adult who had not completed high school; (2) in poor families in metropolitan, central cities, or nonmetropolitan areas of the South; or (3) in households in which the usual language was not English. The bulk of the document contains tables of data which illustrate these trends. (Author/AV)