A project to investigate the effects on the language development of secondary school pupils of a study of transformational grammar as represented in the Oregon English Curriculum involved 250 students in a large, coeducational high school near Auckland, New Zealand. The students were divided into three matched groups who studied different English programs over a period of three years. The three programs were the whole Oregon Curriculum (identified as TG) of transformational grammar, rhetoric, and literature; the Oregon Curriculum without the grammar thread (RW) but with extra reading and creative writing; and a textbook based program that focused on traditional grammar and incorporated supplementary literature from other school resources (LLE). The aspects of language on which the growth of students was compared included essay writing, sentence structure, usage, spelling, reading comprehension, vocabulary, literature, and attitudes. The results presented in both narrative and tabular form show that the effects of grammar study are negligible in terms of improving writing skills, and that the attitude of the RW group toward English as a subject of study was more positive than that of the other two groups. (AEA)