In this paper we consider several factors affecting performance in principles of economics courses that have received little or no previous attention in the economic education literature. While these variables reflect a diverse group of factors, they have all become important in recent years, and are likely to remain so in the future. Specifically, we examine: 1) the effects on student learning and grades of assigning graduate student instructors who speak English as a second language; 2) the effects of alternative semester formats that change the intensity and duration of instruction in principles courses; 3) the effects of mixing freshmen and upperclassmen with sophomores who have tradi