Approximately 1,225 Mexican American and Anglo American children in grades 1-6 (ages 6-14) from California, Colorado, New Mexico, and Texas were tested using school achievement and IQ standardized tests and four Piagetian-derived measures (Cartoon Conservation Scales, Water Level Task, Figural Intersection Test, and Serial Task). The field study's goals were to examine the: (1) interrelations among the four neo-Piagetian measures in a Mexican American sample which varied as to geography and socioeconomic status; (2) neo-Piagetian measures' psychometric properties; (3) relation between developmental level as assessed by neo-Piagetian procedures and IQ as assessed by standardized measures; (4) extent of field-independence as measured by the Water Level Task; and (5) sex differences in performance on the tests. The developmental measures were given to all subjects irrespective of site while the standardized achievement and IQ tests were given on a site specific basis. Among the standardized tests were: Otis-Lennon Mental Ability Test, Inter-American Series; and Peabody Picture Vocabulary Test. Some findings were: except for the Serial Task, the neo-Piagetian measures possessed high reliability, homogeneity, and validity; and these measures exhibited a developmental progression of performance scores across age in accordance with Piaget's theory of cognitive development. (Author/NQ)