The expression ‘Oh’ in natural conversation is a signal topic in the development of the Epistemic Program (EP). This article attempts to bring into view a sense of place for this simple expression in the early literature, beginning with ‘Oh’ as a ‘change-of-state token’ and through its subsequent treatments in the production of assessments. It reviews them with an interest in two allied developments. One is the rendering of ‘Oh’ as an expression that ‘indexes’ epistemic structure. The other, pursued in the detail of transcript in Part 2, is how, as of this rendering, the literature manages its tasks of ‘animating transcript’, or how we portray ordinary talk as social action. We think these two moves are closely connected within the EP. And we think they yield a very different ‘vocabulary of motives’, different from the natural language studies of conversation analysis (CA). Our discussions address in turn the central phrases of our title.