This thesis is a discourse analysis of spoken argumentation in the Adult ESOL classroom. It investigates the ways in which it emerges and unfolds and also how teachers and students position themselves and each other in argumentation and how they are positioned by pedagogy and policy as well as by their histories. The principal focus is on verbal argumentation but some attention is also given to a more multimodal analysis. Argumentation is conceptualized in terms of competing and consensual voices (Costello and Mitchell, 1995). These voices are further conceptualized as situated speaking positions and, therefore, as identity positions. The study explores the ways in which argumentation unfolds, the ways it seeks to persuade and the identity work this involves. Argumentation is connected to wider questions of citizenship and democracy, with the Adult ESOL classroom seen as the agora for the wider enactment and modelling of full democratic citizenship.