Although proficiency in vocabulary has long been recognized as basic to reading proficiency, there has been a paucity of research on vocabulary teaching and learning over the last two decades. Recognizing this, the U.S. Department of Education recently sponsored a Focus on Vocabulary conference that attracted the best-known and most active researchers in the vocabulary field. This book is the outgrowth of that conference. It presents scientific evidence from leading research programs that address persistent issues regarding the role of vocabulary in text comprehension. Part I examines how vocabulary is learned; Part II presents instructional interventions that enhance vocabulary; and Part III looks at which words to choose for vocabulary instruction.