The theory of truthmaking has long aroused skepticism from philosophers who believe it to be tangled up in contentious ontological commitments and unnecessary theoretical baggage. In this book, Jamin Asay shows why that suspicion is unfounded. Challenging the current orthodoxy that truthmaking's fundamental purpose is to be a tool for explaining why truths are true, Asay revives the conception of truthmaking as fundamentally an exercise in ontology: a means for coordinating one's beliefs about what is true and one's ontological commitments. He goes on to show how truthmaking connects to analyticity, truth, and realism, and how it contributes to debates over nominalism, presentism, mathematical objects, and fictional characters. His book is the most comprehensive exploration to date into what truthmaking is and how it contributes to metaphysical debates across philosophy, and will interest a wide range of readers in metaphysics and beyond.