In a series of lectures during Spring 1966 Sacks examines an introduction sequence from a group therapy session where a new member is introduced (Sacks 1995 p268-312). Within these lectures, Sacks shows how it is possible to analytically approach interaction as sequentially organised and multi layered, where the categorial relevancies and sequential actions unfold within a mutually elaborative and layered texture over the course of the sequence. By tracing his analysis over the series of lectures the chapter highlights the way Sacks’ artfully brings in to view the analytic power of treating sequence and category work as entwined, before then discussing how this insight continues to be the central analytic puzzle that I have constantly returned to in my own research.