Q. It has come to my attention, over the last few years, that people are now using the phrase “different than” instead of “different from.” Please warn your readers against this gross misuse of the English language!
A. Yikes—instead, let’s dodge this bullet. Although British English eschews the use of “different than” and Chicago prefers to avoid it, it’s not incorrect, and in fact is sometimes the more elegant choice when followed by a clause. Various dictionaries and grammars support this view, including not just CMOS (see the entry for “different” in the glossary at 5.250) but also Fowler’s Modern English Usage and Merriam-Webster.