Leader debates have become a pre-eminent means of campaign communication in numerous countries and were introduced in the UK relatively recently. However, the quality of such communication is, to put it mildly, open to question. This article uses the Discourse Quality Index (DQI) to assess the deliberative quality of the 2010 UK party leaders' debates. When scrutinized in isolation, and viewed through the full prism of the DQI categories, the quality of discourse evidenced in the debates is a relatively poor reflection of mainstream idealizations of democratic deliberation. However, when the analysis is rehoused within the wider project of constructing a deliberative system in the UK, and is given a comparative institutional dimension, the epistemic value of the debates is revealed. The relatively high level of justification employed by the party leaders suggests that the debates are a valuable means for the mass communication of reasoned defenses of manifesto pledges to the public sphere, and that they are likely to have a significant educative effect. Moreover, we argue that sequencing such debates with representative deliberative fora will force elites to improve the deliberative quality of their communication and enhance the reflective capacity of the viewing public. We therefore agree with Shephard and Johns (2012, p.15) that, 'given the centrality of the debates to the dynamics of the 2010 campaign (and, albeit less directly than anticipated, to the eventual outcome), they warrant closer scrutiny'. This article scrutinizes the debates in a very specific manner. Our aim is to evaluate the leaders' debates through the lens of deliberative democracy. More specifically, we aim to measure the 'deliberativeness' of the discourse employed during the debates and to comment on the role leaders' debates may fulfil as part of a wider deliberative system in the UK.There are differing anecdotal impressions of the British leader debates' deliberative credentials. During the 2010 and 2015 campaigns, various commentators expressed concerns and were therefore sceptical about the debates' contribution to the democratic process. The main criticisms were that the debates promoted 'style over substance ' (see Freedland, 2010;Marqusee, 2010;Waweru, 2010); that their novelty, in the words of the outgoing and incoming Prime Ministers respectively, 'clouded the need for policy to be debated' (Watt, 2010) and 'sucked the life' out of the election campaign (LUCRC, 2015); and that ultimately 'as Socratic dialogues aimed at uncovering the truth the debates were, almost inevitably, failures ' (Pattie and Johnston, 2011, p.150). These appraisals echo criticisms leveled at the use of the televised debate in the USA, where it is an established feature of the campaign landscape (see, inter alia, Auer, 1962; Bitzer and Router, 1980;Lanoue and Schrott, 1991).If true, this would seriously undermine one of the main justifications for such debates, which is that their educative effect will improve the quality of democratic decision maki...