his is the first English translation of the Prolegomena iuris naturalis by Gottfried Achenwall (1719–1772). In this book, Achenwall presents the philosophical foundation for his comprehensive theory of natural law. The book is of interest not only because it provides the basis for a careful, systematic, and well-respected eighteenth-century theory of natural law in the Leibniz-Wolffian tradition, but also because it sheds important light on the work of Immanuel Kant. Achenwall’s work influenced Kant’s legal and political philosophy as well as his ethics, and it is indispensable for understanding Kant’s Feyerabend Lectures on Natural Law and his Metaphysics of Morals. The present volume complements the translation of Achenwall’s handbook, Natural Law.