The use of online course offerings in college has grown sharply in recent years. Previous research, while limited, is inconclusive in determining expected student performance in online versus a traditional lecture format. This paper focuses specifically on student performance in introductory microeconomics classes, analyzing learning differences between those in online and traditional lecture classes. In addition to comparing overall performances, the researchers tested further to determine if gender, ethnicity, major, and levels of achievement and aptitude are factors in explaining differences in performance between lecture and online classes. They then studied the differences between the groups within lecture and online classes to determine if there was a gap in performance due to gender, ethnicity, major, effort, or aptitude. One objective for this study is to better predict student performance in online versus traditional lecture course formats.