A newly reorganized, up-to-date overview of key reference works in philosophy, reflects a veritable explosion of reference sources, both print and online, published over the past decade. Nearly 300 of the 700+ entries consist of new material, with an additional 50 entries substantially revised and updated. English-language sources are emphasized, but important non-English works are also well represented. For professional philosophers, philosophy educators, students from beginning to graduate, and librarians. This guide represents a substantial updating and complete re-organization of the author's 1997 , 2nd edition (1st edition, 1986). It reflects a veritable explosion of reference sources, both print and online, in the field of philosophy over the past decade. Nearly 300 entries (or 40 percent) are entirely new. An additional 50 or so entries have substantial revisions recording new editions, changes in serial publications, series, and websites, or additional volumes completed in multi-volume sets. In addition, it has been entirely re-organized along topical lines. Each of its twenty-three chapters is divided into four sections: (1) general sources, (2) history of philosophy, (3) branches of philosophy, and (4) miscellanea. This new arrangement accords better with the greatly expanded range of philosophy reference sources and makes it easier for the user to identify related sources of different types (bibliographies, dictionaries, web gateways, etc.) on the same topic. Like its predecessor , the 3rd edition aims to serve a diverse audience of professional philosophers, philosophy educators, students from beginning to graduate, and librarians. All entries include generous annotations that are often evaluative as well as descriptive. English-language sources are emphasized, but non-English works important to researchers or of interest to users with facility in other languages are also well-represented.