Three preschool tests were administered to a group of 583 kindergarten children in order to investigate the effects of age, ethnicity, sex, socioeconomic status level, and language background on the scores of two product tests (one verbal and one nonverbal) and one process test. In addition, the study examined how student differences on process variables contribute to score disparities on product tests across ethnic and language background groups. The Cooperative Preschool Inventory—Revised Edition (PI), Drawa-Man (DAM), and Goodman Lock Box were administered to Anglo, black, English-dominant Puerto Rican, and Spanish-dominant Puerto Rican children. Findings were subjected to linear regression analyses. While the scores on all three tests were modified by at least two of the studentattribute variables, the process scores measured by the Lock Box were less affected than the product scores on the PI and DAM. Results are discussed in terms of the difficulty Spanishdominant Puerto Rican children showed in processing cognitive stimuli. Research and programming suggestions are provided for investigations at the kindergarten level where English proficiency varies within ethnic groups.During the past decade, efforts have been directed toward the early identification of children likely to fail in school. Professionals estimate that from 15 % to 40 % of all kindergarten children have developmental lags (Bradley, 1975;Feriden & Jacobsen, 1970;Kirk, 1972; National Advisory Committee on Dyslexia and Related Reading Disorders, 1969). While the need for accurate preschool assessment is apparent, there is considerable evidence showing that score differences on product (versus process) tests occur when student groups have dissimilar background characteristics. Differences on product tests across race groups at the preschool level are well documented, with Anglos obtaining higher scores than minority children (Jensen,