Many parents on a southwestern Manitoba (Canada) Indian reservation are troubled by the small number of high school students who graduate. Much of the failure can be attributed to the generally poor writing skills of aboriginal students. To increase the students' writing ability, a computer-assisted instruction program emphasizing writing and thinking was implemented for students in grades 7-9. The purpose of this study was to investigate whether students receiving computer-assisted writing instruction would outperform students receiving traditional writing instruction (using pencil and paper) on the language arts component of a standardized diagnostic test. Following a quasi-experimental design, the researcher applied both a pretest and a posttest to the experimental and control groups. Prior to the introduction of the "KnowledgeBuilder" writing program and again at the end of the school year, the students in grades 7-9 of two southern Manitoba Indian reserves were administered the Canadian Test of Basic Skills, and the mean scores for each grade of the two schools were compared. While the findings of this study showed no significant difference between the groups, the experimental school's teachers felt there was an overall improvement in the quality of expository writings. Thirteen tables present results of the study and descriptions and comparisons of the control and experimental groups. (Author/AEF)