This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. The book synthesizes the current state of college- and career-readiness research, best practices in measurement and diagnostics, and leading intervention practices designed to prepare students for life after high school. It focuses on the definitions of college and career readiness. The book also expands the definition of college and career readiness even further by including noncognitive skills. It also addresses the role of general cognitive ability in college admissions and outcomes, career hiring and performance, and later-life achievement. The book then explores the use of college-readiness assessments in college placement decisions. It then describes the importance of intervening early in supporting college and career readiness. The book then discusses the academic interventions, with a specific focus on best practices in developing mathematics pathways between high school and college.