The theory of capital structure is one of the most exciting and complex topics in corporate finance. After many years of debate it is still extremely difficult to provide a conclusive answer to the question which capital structure maximises the value of a company and what factors determine the optimal mix of debt and equity capital.This book provides a comprehensive introduction to capital structure theory and investigates its practical relevance in the German market. The main objectives are to explore the link between capital structure theory and corporate practice and to test determinants of capital structure choice empirically.The book has been written for students, researchers, and academics, but also for practitioners seeking empirical evidence of capital structure theory and an empirical model that can be used to estimate the optimal level of debt for an individual company in relation to an existing industry optimum.