For more on indexing, see the Chicago Manual of Style (14th edition), Chapter 17.

You as author are the best-qualified person to prepare the index because you know the content and organization of your book well. And you--not the computer--are the best person to decide what to include, how to word entries, when to use subentries and cross-references, and how to subdivide entries. If other commitments prevent you from preparing the index, employ someone else to do this under your direction.

MAIN STEPS IN INDEXING

• Many authors find it convenient to index initially on 3 by 5 cards. Go through the proofs, and when you find an indexable item on a page, prepare a card: Record the key term or subject; perhaps add a statement about the key term (in the final index such modifiers may be dropped or may become subentries); indicate the page number. If you alphabetize the cards as you go along, you will not have to write the same entries twice but simply add new page numbers.
• Edit the cards after you have gone through the proofs twice: group entries, determine subentries, and include cross-references (but keep cross references to a minimum).
• Type the index double-spaced and print it out on standard-size paper.
• Proofread to see that entries aren't scattered under synonyms, and that cross-references lead to other entries. Check capitalization, punctuation, spelling, and alphabetization.
• Submit the completed index to the Press both as double-spaced hard copy and on disk. Microsoft Word 98 for Mac software is preferred.

The thoroughness of your indexing should be consistent from start to finish. (It's easy to fall into the trap of overindexing the early pages.) And remember, it's easier to prune a lengthy index than to redo a skimpy one. Use the following as a way to judge the thoroughness of your index, not as a quota or goal:

For a book with one overall index, five or six references per page is about right; for a separate subject index, for instance, the total number of entries (including subentries and sub-subentries) should be about twice the number of text pages. Another rule of thumb is that a good index might take up about 5 percent of the total number of pages. Use these figures as a way to judge the thoroughness of your index, not as a quota or goal.

For specifics about compiling your index, see below.

COMPILING THE INDEX

Ask yourself how the reader would use the index. What topics will he or she be likely to look up? Where would you look for the topic if you were unfamiliar with the subject?

Main Entries and Subentries

• Main entries usually come from the heads and subheads in your text, since these provide the framework for ideas.
• Spell main entries as in the text and include cross-references for spelling variations ("Dostoievsky. See Dostoyevsky").
• Make the most-often-used term the main entry, turn synonyms into cross-references.
• Index by nouns (single words or short phrases). The adjective "absolute," standing alone, is not a proper entry; "absolute humidity" is. (An alternative would be "humidity, absolute.")
  • Index concrete nouns: "characteristics of God" is an acceptable topical heading in the text, but "God, characteristics of" is the way to index it. The reader would not be likely to look for information under the abstract noun "characteristics."
  • Entries should be nouns or noun phrases, not clauses and not adjectives. List the key word first ("Dostoyevsky, birth of" not "birth of Dostoyevsky").
  • Don't index casual mentions. Make an entry only when an idea is discussed. Remember, though, that one reader's trivia is another's special interest, so if an entry for a topic is foreseeably useful, do include it.

Cross References

Cross-references guide your readers from one topic to related topics. As a rule, use "See also" to lead from a general term to others included within its meaning ("nineteenth-century novelists. See also Dickens and Dostoyevsky").

Cross-referenced entries do not have page numbers but refer to the main entry (never to another cross-referenced entry). The exception is when fewer than five page numbers and no subentries follow a main entry; in this case, repeat the numbers after the synonym rather than cross-referencing.

If more than six page numbers follow an entry, use subentries. Subentries are specific aspects of the main entry and are listed alphabetically under it. If too many subentries follow an entry, promote them to main entries. Sub-subentries divide subentries and should be used sparingly, just to keep your subentries from having more than six page numbers after them.

INDEX STYLE

• Lowercase entries and subentries that are not proper nouns or names.
• Indent subentries under each main entry. Do not use tabs. Never use spacebar.
• Do not run in subentries. Start each one on a new line, indented.
• Cross references: We use the indented-style index, not run-in style (see Chicago Manual 17.15, 16). Therefore, place cross references right after the main heading, as in Chicago Manual 17.60. See also and see are preceded by period but do not end with a period.
• Add a comma between the entry and the first page number.
• Be sure to add all accents and special characters.
• For inclusive numbers (121–22; 1956–60), use an en dash instead of a hyphen.
• See and See also are always italicized, except when the reference itself is italicized: See Revolution, American; but: See also Little Women.
• Leave extra space between each alphabetical section.

Style for Page Numbers

• A typical entry would be: Dickinson, Emily, 23–24, 101–2 (never 101–02), 115–18 (not 115–118 of 115–8), 300–302.
• Full page numbers appear only with 00 numbers; example: 300–302.
• If you use bold or italics for some page numbers (for example, to indicate references to figures), explain their significance in an introductory note.

Indexing Footnotes and Endnotes

• Index notes only when they amplify the discussion in the text. Do not index notes that merely document the text.
• When indexing footnotes or endnotes, include both the note number and the page number, thus: 120 n. 10.