Research in Mexican and British schools provides an empirical basis for arguing that, by the use of certain kinds of interactional strategies, teachers can enable children to become more able in managing individual and joint reasoning and learning activities in the classroom. The research described is based on a sociocultural conception and analysis of education, which focuses on the ways that children can be inducted into the communicative and intellectual activities of the classroom as a "community of enquiry". The research has provided (a) an account of strategies teachers use, and for relating teacher's scaffolding to the interactive process of knowledge construction; (b) an analysis of ways that children talk when working together on joint activities; and (c) a practical method for promoting children's effective collaboration, communication, reasoning and learning, successfully tested with British and Mexican primary school children. The results of the research are discussed in relation to a Vygotskian conception of the relationship between "intermental" (social) and "intramental" (psychological) development.