Vertical Lists, Bullets

Q. I have a question about bulleted lists and capitalization. I’ve always written lists with the first word capitalized and then subsequent words, not (unless proper nouns of course). A colleague believes that every word other than prepositions or conjunctions should be capitalized.

—No artificial colors, flavors, or preservatives


—No Artificial Colors, Flavors, or Preservatives

I can’t seem to find a “rule” on this. Any help?

A. When a colleague wants to do something you find bizarre, the burden is on her to produce the rule. After all, CMOS doesn’t have the space to write “Don’t do this; don’t do that” with regard to every possibility. Meanwhile, you might point out that none of the examples of lists or outlines in CMOS 6.127–32 show headline-style capitalization of the items.