This report expands on earlier research that found evidence of strong links between school restructuring and improved learning among students in the first 2 years of high school. This report, based on 1992 National Education Longitudinal Study (NELS) data, analyzes data collected for most of the same students in their last 2 years of high school. The sample was comprised of 9,570 students enrolled in 787 secondary schools nationwide. Hierarchical Linear Modeling (HLM) was used to analyze student engagement and achievement in mathematics, science, history, and reading. The report speculates that restructured schools based on the "organic" model, in which teachers have much greater authority over instruction and curriculum, affect student learning. The organic model is characterized by a common academic curriculum, academic press, authentic instruction, and a collective sense of responsibility. Findings indicate that the presence of organic school-organization characteristics explained much of the improvement in student learning and that the restructuring effects on learning increased during the later years of high school. The report contends that schools, especially high schools, should move toward smaller, more organic structures. The school-within-a-school model could be a promising strategy. Two figures are included. Three different educators respond to the research findings in subsequent articles. (LMI)