In its first half, this article considers whether democratic legitimacy entails deliberative requirements during the reform of constitutions. Norms of widespread direct citizen involvement have emerged in the constitutional law and practice of many countries. Yet corresponding standards of deliberation in democratic constitutional reform remain unsettled. Drawing on theories of deliberative democracy, the article suggests that, to count as democratically legitimate, constitutional reform must safeguard the quality of deliberation. This strong claim is tempered by a view of legitimacy not as absolute, but as a proportionate and comparative concept. Even so, the article identifies an onerous double-requirement for constitutional legitimacy: that reforms must be at once widely participatory and robustly deliberative. Based on this theoretical groundwork, the article's second half evaluates a selection of "deliberative voting" innovations. This focus on voting is largely unique in the literature, and is especially relevant, for it is at the stage of voting that deliberative democratic constitutional reform faces the greatest impediments. Prior to the vote, several new kinds of deliberative fora may be able to enhance deliberation (e.g., Citizens' Assemblies); yet most citizens do not become meaningfully involved in reforms until the final, largely solitary act of voting. The prospects for deliberative democratic constitutional reform may therefore remain limited without new approaches to public constitutional voting. For example, a proposal for "integrated referenda" would partially redefine voting and deliberation - traditionally conceived as separate - by merging voting with deliberative fora such as Citizens' Assemblies. Other potential innovations, aiming to prompt informed and purposive reasoning, include mandated online tutorials before the referendum vote; "preliminary values questions", which ask voters to rank the general constitutional values that should drive reform; and "scaled referenda", which present voters with not one but a range of options clearly stating costs and benefits.