The major aim of this project is to elucidate further the role of working memory in the acquisition of reading skill. Three groups of elementary school students will be recruited. Two groups (N=40 in each) will be poor readers; one group will meet criteria for developmental reading disability and the others will be slow learners. These groups will be stratified (two levels) on teacher ratings of attention deficit disorder (ADD). A comparison group of normal for age readers (N=40) will match the two poor reader groups in severity of attentional problems (major or minor). While all groups will exhibit impairments in working memory, the pattern of sub-component deficits is expected to vary. Especially at issue is why approximately half of ADD children learn to read and spell at an age-appropriate rate despite evidencing working memory dysfunctions (e.g., below normal digit span scores on the WISC-R). Subjects will be compared on a wide variety of tasks that assess reading skill and that tap different components and/or correlates of working memory (e.g., articulation rate, confrontational naming rate, serial memory span). Each of the latter tasks will be done under two or more conditions to explore the role of stimulus type and distractors on working memory. Electrophysiological monitoring will be done during two tasks, allowing assessment of (1) event related potentials to rhyming and non-rhyming word and nonsense word pairs and (2) EEG coherence during mental arithmetic and viewing of word and letter strings. It is expected that slower articulation rates and impaired phonological sensitivity will underlie working memory dysfunctions in the dyslexic and the slow learner groups. The working memory deficits of the ADD only group will be hypothesized to be innate (limited capacity) or strategic and not motivational in origin if incentive conditions do not improve their performance. All three groups to be studied remain troublesome to educators; findings could lead to more efficient remedial approaches.