In this commentary, the author identifies what, in her opinion, has been left out of the discussion of "scale up." She expresses particular concern that the rhetoric of scaling up, and the concomitant assertion of scientific underpinnings for programs brought to scale, may overstate the relation of the developers' programs and program materials to children's learning and undervalue the contribution of teachers' adaptive implementation. Further, the author contends that an over-reliance on standardized test scores as proxy for comprehension and an underspecification of the contribution of various teachers may create faulty contextual associations with learning. This article argues for the funding of a close-up, focused study of teacher variation along dimensions that count, and for a more elaborated view of the context of comprehension instruction and assessment.