The Dallas Independent School District presents longitudinal trends in achievement test scores of students tested in each of its subdistricts from 1976 to 1982. Forms 5, 7, and 8 of the Iowa Tests of Basic Skills were administered. What the quasi-longitudinal and cohort-longitudinal test scores together affirm is that median scores have traditionally been higher at lower grade levels than at higher grade levels. Cohorts of District students had scored high when in grades 1-3 in recent years and then lost ground with their peers in the national norming group over the following 2 or 3 years. The patterns of growth within grades, while indicating that achievement scores have generally improved in grades 1-8 in 1982, do not show that cohorts have yet caught up with their prior performances as younger students 2 or 3 years earlier. In order to catch up, growth within higher grades must exceed growth within lower grades. What has been actually happening is that, while growth generally exists in all of grades 1-8, it is even stronger at the lower grade levels than at higher grade levels. (PN)