This study deals with the grammar of clause combining in Finnish and Japanese conversation. It focuses on the verbal and non-verbal cues which enable participants to define whether a clause-sized unit will end or carry on with another clause-sized unit, generating a clause combination. The participants orient to, at least, prosodic and non-verbal cues in determining the boundaries of clauses and projecting continuation in the form of another clause. Fixed expressions are also significant for projection. In addition, semantic and pragmatic factors play a role. This paper explores where the borders of grammar for interaction, grasped as the knowledge that speakers share and which underlies the development of novel utterances, should be drawn, and whether grammar should comprise, besides morphosyntax, not only prosodic, pragmatic and semantic characteristics but also bodily conduct.