What was J.R.R. Tolkien’s first published scholarly book?

J.R.R. Tolkien’s first published scholarly book was A Middle English Vocabulary.

Published in 1922, A Middle English Vocabulary was prepared with Kenneth Sisam and was designed as a companion to Sisam’s Fourteenth Century Verse and Prose. It reflected Tolkien’s academic work on the history and structure of English before his major creative books appeared.

The vocabulary helped students approach Middle English texts by explaining words and forms. Tolkien’s expertise in historical linguistics became a foundation for both his university career and his invented languages, although the vocabulary itself is a scholarly reference work rather than a fantasy narrative.

Readers sometimes name The Hobbit as Tolkien’s first book, but that is his first major work of fiction for a general audience, published in 1937. His earlier academic publications included articles and collaborative scholarship, making the 1922 vocabulary an important early book-length publication.