This book explores the role of time in rational agency and practical reasoning. Agents are finite and often operate under severe time constraints. Action takes time and unfolds in time. While time is an ineliminable constituent of our experience of agency, it is both a theoretical and a practical problem to explain whether and how time shapes rational agency and practical thought. The essays in this book are divided into three parts. Part I is devoted to the temporal structure of action and agency, from metaphysical and metaethical perspectives. Part II features essays about the temporal structure of rational deliberation, from the perspective of action theory and theories of practical reasoning. Part III includes essays about the temporal aspects of failures of rationality. Taken together, the essays in this book shed new light on our understanding of the temporality of agency that coheres with our subjective sense of finitude and explains rational agency both in time and over time. Time in Action will be of interest to advanced students and researchers working on the philosophy of time, metaphysics of action, action theory, practical reasoning, ethical theory, moral psychology, and rational justification.