This study focuses on the effect of using a computer-based competitive learning system called LearnStar, as supplementary instruction in introductory chemistry courses. The outcomes evaluated were of student performance on classroom exams, the cumulative final, overall course grade, overall DFW rate (the percentage of student receiving a D, F, or withdrawing from the course), voluntary attrition (the percentage of successful students that elected not to advance into general chemistry), and total longitudinal attrition (the total percentage of introductory chemistry students who did not enroll in general chemistry the following semester). The students who were involved in LearnStar performed significantly higher on the three classroom exams (ANOVA, p less than 0.001), the cumulative final (ANOVA, p less than 0.001), and in their overall class grade (ANOVA, p less than 0.001) when compared to the control group who had not received supplemental instruction. The overall DFW rate for the LearnStar group was significantly lower (z test, p less than 0.001) than the control group, as was voluntary attrition (z test, p less than 0.001) and total longitudinal attrition. After successful implementation of the LearnStar program, the supplemental instruction was removed, and it was determined that student performance in the posttest group returned to the baseline levels of the pretest control group. (Contains 3 figures, 6 tables and 1 note.)