It is self-evident that, given a group of very active young children and four walls within which to contain them, certain decisions have to be made fairly rapidly: what happens, where it happens, and when seem to be the most obviously pressing. When and how does differentiation come into play? Is it only when making decisions about grouping the children? In this article, the author contends that differentiation can and does happen at every level in the context of the infant classroom. She asserts that some manifestations of this process are designed as a permanent part of the classroom-structure and are explicitly and consciously undertaken; for example: "My better readers sit at that table." Others are entirely temporary, for example: "Those who want to help with planting bulbs, put your coats on." In between lies an enormous number of decisions about when, what, and how the children learn, which, while not necessarily being conscious acts of differentiation, may very well reflect unconscious values and almost certainly reveal basic assumptions about the nature of learning. The author describes what a non-differentiated classroom looks like, one in which a teacher really knows the children as individuals, and every child is valued. [Annabelle Dixon was co-editor of FORUM from the summer of 1998 until her untimely death in May 2005. The article reproduced here is based on an article that first appeared in FORUM in 1984, Volume 26, Number 2, with the title "Divided We Rule." At that time, she was a practicing infant teacher, and deeply concerned about the ways in which the widespread practice of differentiation affected young children's learning. The version printed here has been extended, edited and retitled, drawing on a longer, later version, unpublished as far as is known, which she circulated to friends and colleagues in 1986.]