Following from Jefferson's (1979) observation that laughter can invite reciprocal laughter, this article explores an interactional pattern that underpins regularities in the occurrence behind shared and non-reciprocated laughter. Analysis of a large collection of instances in terms of their sequential position and contribution to the trajectory of sequences, revealed a sticking pattern: that shared laughter is often associated with topic termination. After exploring several instances of this sequential pattern and considering how laughter contributes to a closing trajectory, I then analyse excerpts where laugh invitations are refused by recipients who overlap with contributions that pursue topical talk. In these it appears that participants orient to the potential topic termination relevance of shared laughter, and thus refuse the invitation in order to add to topical development. In this way, the article adds to a body of conversation analytic research that demonstrates that there is no simple stimulus-response relationship between humour and laughter and that the occurrence or absence of laughter at an appropriate juncture may result from orientation to interactional considerations such as the ongoing trajectory of the talk.