“You betcha I’m a ’Merican”

This article studies you bet and related phrases when they are used as a parenthetical and as a free-standing response. Drawing on a range of corpora, we provide both contemporary and historical perspectives on the set of pragmatic expressions that has largely escaped scholars’ attention. Synchronically, we demonstrate that they are colloquial American pragmatic markers to express speaker certainty/affirmation or to respond to thanks. Diachronically, these markers are hypothesized to have developed out of main clause usage with a clausal complement (‘the matrix clause hypothesis’); however, our historical corpus evidence does not straightforwardly support this hypothesis. Instead, we suggest that multiple constructions might have been involved in the emergence of the pragmatic markers, namely, wh-interrogatives (e.g. what will you bet (that) …?), modal constructions (e.g. you may/can bet (that) …), and main clauses with a reduced complement (e.g. You bet I do).