The purpose of this study was to explore the effectiveness of using ALEKS (Assessment and Learning in Knowledge Spaces [3]), an online interactive learning system, in teaching a college algebra course at a university. This system was used to replace traditional assignments. The study was conducted in eight college algebra courses in the Fall 2003 semester at a small university in the Midwest. Four sections used ALEKS, and four sections taught in a traditional fashion served as a control group. We examined the effectiveness of the technology in helping students gain the necessary knowledge to be successful. Students working with ALEKS online worked at their own pace, enhancing mathematical ideas they already knew and building on this knowledge in a mastery learning environment. (Contains 8 tables.)