Educational researchers have conducted numerous studies regarding the effects of class size on student learning, yet the disparity of their findings make it difficult to draw overall conclusions. This paper first provides a description of some of the major class size studies in an effort to illustrate this point. Next, a research approach is suggested which might yield more definitive conclusions by carefully accounting for the additional contextual factors which surround class size. In addition to giving particular attention to context, this involves focusing on the mediating effects between class size and achievement and measuring achievement with classroom-level assessments.