Research on middle-level education and the relationship between grade-span configuration and educational outcomes is reviewed in this paper. Discussions include the evolution and growth of middle schools in the United States, differences between middle and junior high schools, and outcomes of middle-grade organization. Two national trends are identified--a reorganization of middle-level schools that favors a 6, 7, 8 grade-span configuration and a replacement of reforms for administrative purposes by those that meet student needs. Findings on different programs' effectiveness in meeting student needs and the relationship between grade organization and educational outcomes are inconclusive. Significant differences are identified in the implementation of various programs across different grade spans. Four tables and one figure are included. (81 references) (LMI)