Q. I am trying to find out when you write if you say “an MBA” or “a MBA.” Here is the example I’m trying to figure out: He earned an MBA from Harvard Business School and a BS from the Wharton School, University of Pennsylvania.

A. Write what you say. MBA is an initialism, pronounced “em be ayy” (or something like that). It begins, then, with a vowel sound: write “an MBA.” On the other hand, write “a master of business administration degree.” (For definitions of initialism and other types of abbreviations, see CMOS 10.2.)