Time has been philosophically and scientifically problematic for millennia, and chronology has been problematic since people started to doubt the seven-day Creation—what is a day, anyway?—Methuselah's age—what is a year, anyway?—and the number of years since Creation—does the Creation clock start on the first day of work or on the day of rest? The ontological status of time and the epistemological necessity of chronology were central topics of Enlightenment philosophy, on the cusp of the New Philology and historical lexicography. From the eighteenth to the twenty-first century, philosophical and scientific notions of time and chronology have been strangely analogous to uses of chronology in historical lexicography, and the analogies alert us to conceptual and practical problems. The special issue thus grounded in intellectual history, the introduction describes the nine articles the issue comprises, with an eye to the special issue's special interests. The issue divides into four parts focused respectively on (1) dates and dating; (2) periods and periodizing; (3) the concepts history and historical; and (4) chronology and the user-interface.