This study identifies key mechanisms through which a young child operates with external knowledge in her immediate social context. Central to this is the child's capacity to draw on discourse-based understandings which have become evident in prior interaction. These understandings are shown to inform and shape various aspects of the child's behaviour, notably request selection, the emergence of new request forms and various kinds of child distress, and they form the 'context' to which the child's actions come to be increasingly sensitive. In contrast to studies which analyse development under different headings, such as language, emotions and cognition, Tony Wootton links these aspects in his examination of the state of understanding which exists at any given moment in interaction. The result is a distinctive social constructivist approach to children's development.