Things alphabetized in telephone books

LASTNAMES

They're listed after first names but come first in directories.

Telephone books organize entries alphabetically by last names, making them the primary way listings are sorted. The clue hints at this common practice, where "things alphabetized" refers to the surnames rather than first names or other details. The answer "LASTNAMES" directly reflects this structure, as it’s the standard method for arranging names in directories. No wordplay is involved—it’s a straightforward reference to how phone books are traditionally organized.