This paper reports on developing research into the learning potential of extended talk, (i.e. either spoken monologue or an extended turn-in dialogue). Despite a widespread belief that the ability to speak at length is personally, socially and professionally empowering, relatively little research has been undertaken into ways in which extended forms of talk can be nurtured and sustained in the classroom. This is arguably because theorisation of the relationship between learning and discourse within the sociocultural paradigm has been overly preoccupied with internalisation. This paper will focus on the development of extended talk for learning and will report on the findings of a coordinated group of practitioner research projects, some of which aimed to develop more extended spoken pupil contributions in primary and secondary school classrooms. Transcripts will be analysed in terms of Lotman's distinction between univocal and dialogic language functions in order to evaluate where particular examples of extended speech reflect productive learning. The paper aims to identify conditions through which extended forms of talk can transform knowledge and understanding and to draw conclusions about ways in which these conditions can be developed and sustained.