The child development knowledge teachers use every day to inform their actions has the potential to both enable and constrain children's learning because it permits teachers to view children from only one vantage point. In this article, the authors argue that in addition to teachers updating their developmental knowledge base, it is important for them to use critical theoretical perspectives. Critical theories examine the power relationships operating in classroom relations, enabling teachers to make sense of the ways their practices can contribute to unequal opportunities for students. After outlining the assumptions framing critical theoretical orientations, they examine some of the early childhood research using these kinds of theories. They conclude by exploring how teachers might approach their work with young children if they use critical theories in addition to knowledge of children's learning and development. For the purposes of this review, the authors concentrate on the research in two areas: responding to diversity and the politics of child-centered practices. (Contains color photographs.)