Fictionalism is the view that a serious intellectual inquiry need not aim at truth. Since 1980, fictionalist accounts of science, mathematics, morality, and other domains of inquiry have been developed. In metaphysics fictionalism is now widely regarded as an option worthy of serious consideration. This volume represents a major benchmark in the debate: it brings together an impressive international team of contributors, whose essays (all but one of them appearing here for the first time) represent the state of the art in various areas of metaphysical controversy, relating to language, mathematics, modality, truth, belief, ontology, and morality.