In the mode of Piaget's stages of development, Harvard education professor Chall sets forth a reading model to delineate ""the difference in the quality of the reading, in the books that can be read, and in the uses to which reading can be put at different stages of development."" She posits six stages: prereading (stage 0); initial reading, or decoding; confirmation, fluency, and ungluing from print; reading for learning the new; multiple viewpoints; and construction and reconstruction--a world view. Though these stages are not rigidly tied to ages (and individuals may move back and forth between them), the order of their occurrence is fixed, as with any stage theory. Apart from the limited supporting evidence Chall adduces (from eye-movement studies, semantic development research, school organizational patterns), the scheme is intuitively sensible. At stage two, as Chall notes, readers must be told: ""Don't fuss too long on each word or you'll lose the thought of what you read"": and, at stage three: ""You really have to try to remember what is said about who, what, when, and how, because these things are impotant to learn."" There are also tellingly different responses, at different stages, to the question, ""Is what you read true?"" The parallels with cognitive development are obvious, yet little work in the area of reading has been done along these lines--so there are implications here for teachers, test-makers, researchers, and parents. And though specific strategies are not spelled out, Chall does suggest certain broad changes (e.g., the well-known ""4th grade slump""--or transition into stage three--might be eased, as of yore, ""by systematic instruction in the reading of subject-matter textbooks""). There will be disagreements and demurrers; there will also be much careful, deserved attention.