Q. I would like to know if a rule exists for the use of “all” and “all of.” Which of these sentences is correct: All the employees submitted vacation requests OR All of the employees submitted vacation requests? Thanks for your help.
A. Chicago style deletes the “of” whenever possible (see 5.220, s.v. “all (of)”). Dictionaries are great for figuring out what words mean. Look up “all” and you’ll learn that it can be used as an adjective modifying a subject (“all employees”) or as a pronoun subject, which can be modified by a prepositional phrase (“of the employees”). When you write “all the employees,” the latter construction is at work; the “of” is silent but understood.