Based on the idea that knowing which words to use and how to use them are keys to an individual's getting the most from his or her mind, this book aims to improve people's vocabularies. To find out which words should be known, research into the vocabularies of educated adults was conducted by "The Princeton Review." Newspapers from "The New York Times" to "The Wall Street Journal," magazines from "Time" to "Scientific American," and books from bestsellers to classics were analyzed. The book incorporated research on necessary words for those students taking the Preliminary Scholastic Aptitude Test (PSAT), the Scholastic Aptitude Test (SAT), and the Graduate Record Exams (GRE) also. It focused on the words that people misunderstand or misuse, and from these, selected the 823 words that appeared most frequently. The book contains many word drills and special lists of common usage errors, most frequently tested words on standardized tests, and foreign phrases, abbreviations, and terms that a person needs to know to understand finance, science, computers, and the arts. According to the book, knowledge of the 823 words discussed will help a person to communicate effectively, be more persuasive, get more from his/her reading, and score higher on standardized tests. (NKA)