Dark ages is a familiar, if untheorized, term of world history. We propose to generalize that concept, and to reinterpret it as "ages of reorganization." We do this by viewing the two major periods of past dark ages as phases of world community formation—this being one of a cascade of processes that make up world system evolution. This reconceptualization allows us to see contemporary developments as the onset of another millennial age of readjustment, understood also as a world system mechanism of self-organization. It is a means whereby the threatening features of earlier developments—those of the preceding ages of concentration—are reined in automatically, as it were, to contain the dangers that they might harbor. We propose to take up these themes, recently opened up by Sing Chew in two recent papers (2002a, 2000b), and will review the following questions in response (in the light of the recently consolidated "World Cities" database): (1) How robust is the concept of dark ages? (2) Have dark ages been features of world system history? (3) Are there grounds to assume the workings of an evolutionary process? (4) Have we already entered upon the modern age of reorganization?