This report examines the results of a study designed to compare various aspects of sex role development among upper middle, middle, and lower class white and Spanish language heritage children in three different preschool daycare centers. The 168 children studied ranged in age from 30 months to six-and-a-half years. Measuring instruments were devised to assess children's knowledge of gender, and to quantify their attitudes and behaviors toward masculine, feminine, and neutral toys. Classification and sorting skills, sex-typed toy behavior and verbal sex-typing of toys, occupations and peers were evaluated on the basis of children's performance during videotaped interviews. Although the results indicated general agreement between the two sexes, the two ethnic groups, and across ages about verbal and behavioral sex-typing, ethnicity was found to be a significant factor in measures of gender knowledge and classification skills. A list of references, description of instruments, sample interviews, and children's line drawings are appended. (JCD)