The most effective way to build high proficiency in English vocabulary is to know Greek and Latin prefixes, suffixes, and roots that are commonly attested in English. Therefore, some mastery of the Greek and Latin roots is indispensable in achieving advanced academic English vocabulary in humanities, science, and medicine. This book includes some of the most important Greek and Latin roots and offers a comprehensive study of English words that are derived from a respective root. By grouping all English cognates from each root, this book will help students in memorizing difficult words. A detailed etymological analysis is avoided because the main goal of the book is to help students learn English vocabulary, and the historical development of Greek and Latin roots into current English words is presented insofar as it helps to understand English words. Each entry of roots is accompanied by an exhaustive list of English cognates, their pronunciations and succinct definitions, and examples of their usage in contemporary English as well as in classical English literature.