Over the last two decades, scholarship on Kant and modern German philosophy has become increasingly focused on understanding their historical roots. Central to this development is the work of Alexander Gottlieb Baumgarten (1714-62), whose textbooks profoundly influenced later generations of German philosophers. Immanuel Kant (1724-1804), in particular, lectured from Baumgarten's textbooks, including those on moral and legal philosophy, for well over thirty years. Following the recent English translation of Baumgarten's key works, this volume is the first comprehensive reappraisal of the relationship between his and Kant's thoughts on the grounding principles of moral philosophy. The chapters—all written by leading researchers who have shaped or are now reshaping the field—cover the whole range of key concepts in the foundations of practical philosophy: obligation, law, goodness, motivation, imputation, conscience, the relationship between ethics and right, and many more. Later chapters provide a comparative look at Kant's and Baumgarten's place within the wider tradition of natural law. Scholars familiar with the field will discover new perspectives on well-received findings, while newcomers will find a comprehensive introduction to the key topics and debates of current research.