The J. R. R. Tolkien Companion and Guide is a three-volume reference book for J.R.R. Tolkien and his works by Wayne G. Hammond and Christina Scull, published in 2006 by Houghton Mifflin.
The Chronology, the first volume, details the parallel evolutions of Tolkien's works and his academic and personal life in minute detail. The work spans the entirety of his long life including nearly sixty years of active labor on his Middle-earth creations, and draws on such contemporary sources as school records, war service files, biographies, correspondence, the letters of his close friend C. S. Lewis, and the diaries of W. H. Lewis.
The Reader's Guide, the latter half, includes brief but comprehensive alphabetical entries on a wide range of topics such as important characters, a guide to places and institutions in Middle-earth or the real world, details on Tolkien's source material, information about the political and social upheavals through which the author lived, the importance of his social circle, his service as an infantryman in World War I -- even information on the critical reaction to his work and the "Tolkien cult" that emerged after the propagation of The Lord of the Rings. The books meantions many unpublished poems such as Bummsdrápa.