Grade-span configuration refers to the range of grades within a school. Grade span is an important issue to various factions in public education, including advocates of middle schools and rural educators concerned with the association between grade fragmentation and school consolidation. This digest focuses on research that has examined the relationship between grade span and student achievement. While many case studies of grade-span effects in particular schools exist, little research has been done using techniques to control for confounding factors. Five studies using such techniques are briefly described. These used data from 18 New York City schools, 700 rural Louisiana schools, 1,001 Texas schools, 163 rural Maine schools, and 330 Pennsylvania schools. In general, the studies suggest that achievement in the middle grades is higher in schools having an elementary-wide configuration than in those with a middle-grades configuration. In a K-8 configuration, absence of school-to-school transitions and greater continuity of experience may contribute to higher achievement. However, only one of the studies considered the instructional or interpersonal dimensions of school life. Further research is needed to disentangle the effects of grade span from those of its corollaries. (Contains 12 references.) (SV)