The concept of learning disabilities is mysterious and complex. . . . The field has not yet been reliably charted. The best any surveyor can do is to stake out some potentially revealing domains."" Mission accomplished: Farnham-Diggory reassuringly escorts the reader, knowledgeable or not, through the maze of conflicting speculations and inconclusive experimentation, establishing the largely unscientific historical bases for current practice and the likely directions of future research. The influence of early theorists (Strauss, Lashley, Orton, Hinshelwood) falls into place, laying the groundwork for more systematic contemporary efforts, the promising cognitive psychology approaches (which may well dovetail with Bruner's and Piaget's works) and the ideas about hemispheric activity and dominance. Examples of specific syndromes take into account the emotional complications of perceptual difficulty and failure. And in appraising the findings and implications of modern investigations, the author indicates not only methodological obstacles but ethical ones as well. Of the Ritalin investigational impasse: ""One experimental solution would be to put special drugs into the placebo pills--drugs that cause sleeplessness or dizziness and nothing else. . . . Would you be willing to have your child participate in that type of experiment?"" Farnham-Diggory writes with good sense and the respect for nuance and uncertainty which generally characterized the first books in this series. A most commendable exposition.