The sex role development of 3- and 4-year-old middle- and lower-class Mexican American and Anglo American males was compared. The sample consisted of 15 Mexican Americans and 15 Anglo Americans of low socioeconomic status (SES) and 15 Mexican Americans and 15 Anglo Americans of middle SES from day-care centers and nursery schools. Approximate SES of the parents was determined by Warner's Index of Status Characteristics; ethnic classification was determined by the parents' self-classification. Presence of a father-figure and sex of older siblings were ascertained. Teachers were asked to fill out a rating scale to measure adoption. Children were administered Brown's 1956 "It" Scale for Children in the standard form to measure orientation and a "You" form to measure preference. Parametric (analysis of variance) and non-parametric (Kruskal-Wallis one-way analysis of variance and Mann-Whitney U Test) resulted in no significant differences on the "It" Scale either for SES or ethnicity. The teacher's rating scale differentiated between the groups, showing the middle-class Anglo Americans and the lower-class Mexican Americans as more masculine than the lower-class Anglo Americans and the middle-class Mexican Americans. (Author/NQ)