The empirical turn in deliberative democracy has recently generated a considerable amount of academic work. Scholars have tried to operationalize the theoretical dimensions of deliberative democracy into robust criteria in order to evaluate the quality of public discussion. Too few though have systematically compared on and off-line deliberation to analyze the link between the technological formats deployed in a deliberative procedure and the quality of the discussion. This is what this paper is aiming to do through a French case study of a national public debate. Drawing from a revised version of the Discourse Quality Index, we propose a coding scheme for quality analysis which rests on an enlarged definition of deliberation. Our results suggest an obvious link between the nature of the deliberation, its quality and the technological frame of the arrangement: some technical environments seem to be more suitable to deliberation than others.