A N Prior has a special place in the history of postwar philosophy for his highly original work at the intersection of logic and metaphysics. His logical innovations have found many applications in the areas of philosophical logic, mathematics, linguistics, and, increasingly, computer science. In addition, he made seminal contributions to debates in metaphysics, particularly on modality and the nature of time. This volume presents a selection of current research in the areas that were of most interest to Prior: temporal and tense logic, modal logic, proof theory, quantification and individuation, and the logic of agency. Both title and contents reflect Prior's view that logic is 'about the real world', and the orientation of the volume is towards the application of logic, in philosophy, computer science, and elsewhere. Following Prior, modal syntax is now widely applied to the formalization of a variety of subject matters, and tense logic has found numerous applications in computing, for example in natural language processing, logical deduction involving time-dependent data, program-verification, and VLSI. A special feature of the volume is the inclusion of three hitherto unpublished pieces by Prior on modal logic and the philosophy of time, along with a complete bibliography of Prior's published philosophical writings.