This book is a sequel to Time and Modality. Many problems raised in that book have been resolved, and new ones have been raised in their turn. The author has recorded some of these developments, and carried on with some further ones. The book is self-contained, presupposing nothing but a few facts, mostly about the better-known systems of modal logic, which can easily be found in the literature. Topics discussed include the precursors of tense-logic, the Diodorean modal system, topology of time, non-standard tense-logics, the logic of successive world-states, metric tense-logic, time, determinism, and existence.