A study addressed the following questions: (1) whether the recognition of rhetorical functions and techniques in English helps students of English as a Second Language understand written technical information better; and (2) whether students are better prepared to write accurate summaries of scientific or technical texts if they have been taught rhetorical functions and techniques. Subjects were 60 university-bound science students with 6 years of elementary and secondary school training in English as a Second Language, randomly assigned to two groups. In a 3-month period, both groups were taught deduction and comprehension skills at the morphological and syntactic levels. The experimental group was also taught cohesion devices and specific rhetorical functions commonly used in written material for science and technology. Tests of reading comprehension and summarizing skills were devised for the study. Results indicate that subjects in the experimental group gained higher scores in reading cmprehension by giving correct answers to questions requiring reinterpretation, reorganization, and inference. The experimental group also performed better on summary-writing tasks. It was found that written material with few discourse markers and more implicit cohesive items were difficult for both groups. Further research is recommended. (MSE)