This book addresses the role of vocabulary in reading text. The role of vocabulary and reading is a complex one, as reading researchers have long recognized. In 1925, Whipple described the central role of vocabulary thus: “Growth in reading power means, therefore, continuous enriching and enlarging of the reading vocabulary and increasing clarity of discrimination in appreciation of word values” (p. 76). In 1942, Davis described comprehension as comprised of two skills: word knowledge, or vocabulary, and reasoning.