The purposes of this study were: (1) to describe the developmental trends in the control of spoken English grammatical constructions produced by Spanish-speaking Mexican-American schoolchildren learning English in the elementary grades, and (2) on the basis of this description to assess the comparative development of English structures in pupils schooled bilingually in English and Spanish and those instructed only in English in a traditional monolingual school program. The principal hypothesis tested was that there would be no significant difference in the development of English grammatical constructions between Spanish-speaking pupils schooled bilingually and those schooled monolingually. It was also hypothesized that if there should be any difference, pupils schooled bilingually would demonstrate greater syntactic development in their spoken English. The subjects were 115 Mexican-American school children in grades K-3. The effects of three independent variables (grade, sex, and treatment) on the production and development of spoken English were assessed. It was found that bilingual schooling had a positive effect on the development of the spoken English of the pupils. The bilingually schooled pupils produced more language overall and more structurally complex units. For both groups, years in school did account for measurable differences in the use of certain English constructions. (Author/LG)