For the past thirty years, Alvin Plantinga's work in the metaphysics of modality has been both insightful and innovative; it is high time that his papers in this area were collected together in a single volume. This book contains eleven pieces of Plantinga's work in modal metaphysics, arranged inchronological order so one can trace the development of his thought on matters modal. In what follows I will lay out the principal concepts and arguments in these papers