There is a very large population of students who struggle with the transition from the middle grades to high school, raising concerns that high school failures are partially a function of poor middle grade preparation. As a result, middle grade practitioners are grappling with questions about what skills students need to succeed in high school, which markers they should use to gauge whether students are ready to succeed in high school and beyond, and whether it is possible to identify in middle grades students who are likely to struggle in high school and college. This report is designed to provide a detailed picture of the relationship between students' performance in the middle grades (grades five through eight) and their subsequent performance in high school and college among students in the Chicago Public Schools (CPS). Key findings are included to help practitioners and policymakers set realistic goals for improvement. Appended to the report are: (A) Students' College Access and Graduation Rates, Based on High School Performance; (B) Data Definitions; (C) Research Methodology; (D) ISAT Standards and EPAS Benchmarks; and (E) Relationships of All Potential Indicators with High School Outcomes. [See the accompanying briefs: "4 Key Findings for High Schools" at ED553150 and the "5 Key Findings for Middle Grades" at ED553151.]