To contribute to a more differentiated description of the cognitive status of young disadvantaged children, a comparative study was made of achievement test performance of disadvantaged and middle class groups of children. On the basis of published reading test scores, test data were gathered from nine public schools, four of which were selected from among the highest scoring in each of four school districts. The remaining five were selected as representative of conspicuously low scoring schools. The children from the high scoring schools were predominantly from white middle class families. The children from the low scoring schools were predominantly from lower class Negro or Puerto Rican families. Data analysis consisted of an item-by-item comparison of the performances of the two groups on each of the six subtests of the New York State Readiness Test. The smallest differences in the high and low scoring groups occurred on the listening , matching, and copying subtests. The greatest differences occurred on the numbers subtest. The pervasive differences found to exist in every area of intellectual functioning suggest the need for a program designed to promote general intellectual growth at a basic and integrative level. Statistical data are presented in two tables, and a summary of future research to be conducted is included in the text of this progress report. (JS)