The purposes of this study are: (1) to make a contribution to the increasingly urgent evaluation of an appropriate measure of the intellectual potential of South Texas Mexican-American children as studied through the community of Charlotte, Texas; (2) to gain some insight into the intellectual abilities of Mexican-American children of Charlotte, Texas when compared to the national norm; (3) to appraise the effects of bilingualism as it relates to the mental development of first through fourth grade children of Mexican- American parentage, particularly through the WISC from the standpoint of the language in which the test is given; (4) to ascertain the value of tangible (candy) and intangible (praise) reinforcement for each correct response yielded during the testing session.