This book focuses on microeconomic foundations of capital structure theory. It combines theoretical results with a large number of examples, exercises and applications. The book examines fundamental ideas in capital structure management, some of which are still not very well understood in the business community, such as Modigliani and Miller irrelevance result, trade-off theory, pecking-order theory, asset substitution, credit rationing and debt overhang. The second edition also covers capital structure issues related to recent developments in financial technology including crowdfunding and token issues and discusses significant differences between these innovative ways of firm financing compared to traditional debt and equity.  Chapters also discuss the ways in which financial economists were forced to look critically at capital structure after the financial crisis of 2007-2009 and the COVID-19 pandemic, as the problems faced by many companies stemmed from their financing policies. Further the book  analyzes links between capital structure and firm performance, corporate governance, firm strategy and flexibility, and covers such topics as life cycle approach to capital structure management, capital structure of small and start-up companies, corporate financing versus project financing and examples of optimal capital structure analyses for different companies. This comprehensive guide to capital structure theory will be of interest to all students, academics and practitioners seeking to understand this fast-developing and critical area.