Q. If a person has two last names, but they are not hyphenated, like Harriet Beecher Stowe, how do you alphabetize them—by Beecher or Stowe? Beecher is not her middle name. It is her maiden name.
A. In the absence of a hyphen, alphabetize by the final name, as you do with a man’s name. Since it’s usually not possible to know for certain the origin of the name in the middle, it is treated as a middle name (not a surname) by default. Not observing this simple rule would lead to chaos: Chantelle Rutherford Smith would be listed in some directories under Rutherford and others under Smith, even if Rutherford is a middle name she was given at birth. (Note that Spanish names have their own rules; please see CMOS 16.84.)