The first edition of this historical dictionary was published in 2006. For this second edition, Brown and Fox are joined by Julia Weckend. Together they have created a lucid, comprehensive reference work on Gottfried Wilhelm Leibniz (1646–1716), one the greatest modern philosophers. Leibniz was “a polymath without equal in modern times” (p. 1) and contributed to many disciplines, but this dictionary limits its scope to topics related to his philosophy. Entries cover Leibniz’s philosophical ideas, major works, and personal life, among other topics. The authors explain complex concepts in simple terms and show how they connect to other ideas from Liebniz’s philosophy. Cross-referenced entries are bolded, and this feature is especially helpful: Leibniz’s philosophy was a unified system, and ideas and arguments were interlinked with each other. This second edition expands entries on difficult philosophical concepts and includes new entries on Leibniz’s influence on other philosophers. The book also features an introductory essay covering Leibniz’s life and philosophical work, a chronology, and an extensive bibliography of other books on his philosophy. This dictionary is a valuable resource on Leibniz’s life, philosophy, and lasting influence. Highly recommended. Upper-division undergraduates through faculty; general readers.