In most sectors of education, teachers are an integral part of the classroom, and they have large effects on students’ short-run and even long-run outcomes.  We investigate the extent to which this is true in online college education.  Online college courses, which are becoming increasingly popular, may change the underlying interactions between students and their instructors.  Using data from DeVry University, we examine how online courses affect student achievement.  We also provide a decomposition of the variance of student outcomes into the parts attributable to students and professors respectively.  The results suggest that instructors explain very little of the variance of student outcomes in online college courses.  This is true when we examine students who take courses in both traditional and online settings, when we examine professors who teach in both settings, and when we control for selection into who takes online college courses.  The results seem to suggest that substantial standardization in order to capture economies of scale in online education lead to decreased variance in professor actions a reduced role of professors in explaining variation in student learning.