The post-expansions discussed so far are ones that have developed in a sequential environment in which (as noted early on) preferred responses are sequence-closure-relevant and dispreferred responses are sequence-expansion-relevant. With the exception of minimal post-expansions and simple repair sequences, the post-expansions we have examined are generally implicated in disagreement and misalignment.

It is possible, however, to have a sequential environment in which there is a systematic reversal of the ordinary differential expansion relevance of preferred and dispreferred second pair parts. Specifically, in topic-proffering sequences, as we will see, preferred responses engender expansion and dispreferred responses engender sequence closure. In this distinct sequence type, expansion has a very different interactional import, and poses sequential problems of a different character, so much so that the development and extension of these sequences can not be assimilated to what we have been referring to as post-expansion.

We have already had occasion to register the fact that some turn types may do “double duty,” both enacting their own action (questioning, assessing, telling) and serving thereby as the vehicle or instrument for another action. The same utterance (or, more technically, TCU) which does questioning can be doing requesting, or offering, etc. The same utterance which does telling can, by what is told or how, constitute a complaint. The TCU which conveys an assessment can thereby accomplish a compliment or an insult.