The use of computer assisted instruction (CAI) at Indiana University to provide basic grammar review to beginning writing students, and the results of an evaluation of the PLATO system as a learning resource are described. At the time of the evaluation, the CAI curriculum in use was the Language Arts Routing System (LARS). The evaluation involved 24 students in an elementary composition course taught in the English department, 20 students in a beginning newswriting course taught in the journalism school, and 16 students enrolled in a non-CAI section of the same journalism course. A section of the journalism class using CAI and a non-CAI section were administered a standardized test of English at the beginning and end of the semester. Neither of the section instructors spent classroom time teaching grammar. At the end of the semester, the mean score of the non-CAI section was not statistically different than it had been at the beginning, while the CAI section's mean increased by 20 points, which was significantly higher than its starting mean. Results of PLATO pretests and posttests also show improvements in both the journalism and English CAI classes. On-line tests also provided a measure of the teaching effectiveness of 53 grammar areas that comprise the LARS curriculum on PLATO. At the end of the term, 35 of the students in the CAI sections completed questionnaires concerning their attitudes toward PLATO as a learning resource, and PLATO received high marks on nearly every attitude measure. Students compared PLATO to the following learning modes: small classes, self-instructional books, videotapes or films, lectures, and textbooks. (SW)