This paper explores the important relationship between dialogue and cognitive and metacognitive development in young children. The characteristics of dialogue are identified and a case is presented for involving young children in talking to think through philosophical discussion. The paper provides a theoretical context for kinds of metacognitive development that it defines as "me-cognition". It draws on classroom research, including the Philosophy in Primary Schools research project, to describe how the theory and practice of dialogue can be used to develop cognition and "me-cognition" in young children. It concludes that dialogic enquiry is a primary thinking skill from which other skills follow, that Philosophy for Children approaches provide effective methods for dialogic teaching that can support and develop children's capacities for cognition and metacognition. (Contains 1 note.)