This document on early characteristics of high and low achieving black children of low socioeconomic status is part of the ETS Head Start longitudinal study, Disadvantaged Children and Their First School Experiences. In the study reported here, intensive case studies were prepared for those study children who, on a 3rd-grade achievement test, were: (1) significantly above or below the average performance for children of similar ethnic or income status in basic reading and math skills; or (2) significantly deviant from the level predicted by their performance on a test of preacademic skills at age 4. It is suggested that the findings of this report are relevant to the current controversy regarding early identification and screening of preschool children. Intensive study of observer ratings and test performances obtained during the age period 31/2-5 should indicate the extent to which assessment of cognitive, perceptual, affective and social functioning in preschool low income black children can serve to: (1) identify, early, those areas of functioning needing remediation; (2) suggest individualized modes of treatment; and (3) suggest early indices of gifted functioning. Included in the document are chapters on the sample, data collection and processing procedures, results and discussion, summary and conclusions. Appendices include measures used in 1969-74 child test batteries and a summary of data collection activities. (Author/MS)