One of the central predicates of legal regulation of media ownership is that ownership consolidation reduces substantive viewpoint diversity. Appellate courts and, in turn, the Federal Communications Commission have increasingly demanded evidence for this convergence hypothesis, but extant empirical measures of viewpoint diversity sidestep the problem, ignoring diversity, viewpoints, or both. Our Article develops and offers a finely tuned, time-varying statistical measure of editorial viewpoint diversity, based on a new database of over 1600 editorial positions in twenty-five top newspapers from 1988-2004. Using this new measure, we assess the validity of the convergence hypothesis by examining the evolution of editorial viewpoints over the course of five major mergers and acquisitions. Our data reveal complex patterns that defy extant accounts, showing stability, convergence, and divergence of viewpoints in the face of—and depending on the circumstances of—consolidation. These findings fundamentally challenge extant empirical regulatory assumptions—pointing to the crucial role of editorial policies—and deeply inform the viability of the ownership regulations and the interpretation of the 1996 Telecommunications Act.