The findings of several tests are used to describe some learning disabilities and patterns common in lower-class Puerto Rican and Negro children. In particular, perceptual dysfunction is pointed to as a major causal factor in the reading problems of the disadvantaged. In one urban slum school, 40 percent of first graders showed serious dysfunction when evaluated on the Frostig visual perception test, with Puerto Ricans and Negroes scoring significantly lower than whites and Chinese. Based on clinical impressions from 50 cases, the information and vocabulary subtests of the WISC appear to differentiate the disadvantaged from the advantaged. In addition, the Diagnostic Test of Word Attack Skills shows a pattern of inability to distinguish between grapheme and phoneme and to discriminate blends. Although class differences are found in articulation and dialect patterns, problems in these areas do not affect reading achievement. Emotional disturbance among retarded readers is not related to class or ethnic status. It is felt that environmental influences are the likely determinants of perceptual dysfunction, in which the differentiating variable is quantitative. Remediation need not involve devices, but corrective teaching must be specifically appropriate to lower-class rather than middle-class pupils. (NH)