Grades and attendance-not test scores-are the middle grade factors most strongly connected with both high school and college success. In fact, grades and attendance matter more than test scores, race, poverty, or other background characteristics for later academic success. This report follows approximately 20,000 Chicago Public Schools students as they transition from elementary to high school. It is designed to help answer questions about which markers should be used to gauge whether students are ready to succeed in high school and beyond. It also considers the performance levels students need to reach in middle school to have a reasonable chance of succeeding in high school.