I now want to introduce another concept for understanding how we lay the foundations for joint intellectual activity: ‘conversational ground rules’. The original use of the term ‘ground rules’ was in sport, to refer to the fact that a particular playing field or ground might have local conventions, perhaps created to take account of its special physical features, which visiting players would need to be made aware of and accept. It is now commonly used to mean special or local conventions of behaviour in any area of life. By ‘conversational ground rules’ I mean the conventions which language users employ to carry on particular kinds of conversations.8 Conversational ground rules are part of the context of any conversation. They consist of the knowledge, which may not be made explicit by speakers, about how to ‘do’ certain kinds of talking. Generally speaking, for spoken language to be used for effective communication, participants need to have this kind of shared understanding and agreement about what to do to make it happen.