Q. I am editing a series about the Communist Party of Italy in the early 1900s. My question is specifically whether to capitalize “communist” when used as an adjective. For instance, when the work references workers who are sympathetic to communism, should I refer to them as “Communist workers” or “communist workers”? Similarly, would I capitalize the C in the following phrases: “communist cells”; “communist vanguard”; “communist program”?

A. You could draw a bright line and use a capital C only to refer to the emerging Italian Communist Party and its members and adherents. The philosophy or program of communism and those who are sympathetic to it or otherwise identify with it would get a lowercase c. A “Communist,” then, would be a party member, whereas “communist workers”—and “communist cells,” “communist vanguard,” and “communist program”—would refer to workers (or cells etc.) who espouse communism, whether or not any of these instances also imply party membership or affiliation. If this distinction seems difficult to maintain or unhelpful to readers (perhaps the series also discusses the program of Communism that became official in the Soviet Union), you might apply a capital C to all references to communism, regardless of how the word is being used. See CMOS 8.66 for some additional considerations.