The relationship between the development of rational public discourse and the expansion of democratic participation provides a focus for the comparative and historical analysis of the public sphere. Major scholars disagree, however, on the character of this linkage. As the contributions to this symposium demonstrate, the resulting debates have generated a rich literature in historical sociology. For Charles Tilly, public discourse and democratic participation proceeded largely in tandem, tracing out one important lineage in the history of democracy. An alternative understanding, informed by the early work of Jürgen Habermas, produces a more conflicted account of the tensions between democratic inclusion and rational deliberation. In their contributions to this symposium, Craig Calhoun and Andrew Abbott reconstruct the shifting and contested public arenas of London and Chicago. In an essay written after the original session for which my comments were crafted, Andreas Koller outlines a substantial agenda for comparative historical research on the public sphere.