Alphabetizing

Q. I am alphabetizing book titles in our elementary resource library. Would the title In the Days of Missions and Ranchos be filed under I for In or D for Days? I think it should be I but our district office said D.

A. If the folks in the district office have a system that they follow for the sake of consistency and they say to file such a title under D, file it under D and note for future reference that prepositions at the beginning of titles are ignored in alphabetizing. If there is no district-wide set of rules for alphabetizing and you wish to follow Chicago, alphabetize your book under I (after running it by the district office). Please see CMOS 16.53: “Unlike articles, prepositions beginning a title always remain in their original position and are never dropped, whether in English or non-English titles—nor are they ignored in alphabetizing.”

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]