Writing an index begins with a change of perspective. The author knows where every idea sits in the manuscript, but the reader does not, and the index must be built from the reader's side of that gap. Each entry should answer one question: where would someone look for this?
What Is an Index Page in a Book?
An index page is an alphabetical list of names, topics and concepts placed in the back matter of a nonfiction book. Every entry is followed by locators, usually page numbers, that point to the passages where the item is discussed. Entries may carry subentries and cross-references to guide readers who search under a different term.
Unlike a table of contents, which follows the order of the book, the index follows the alphabet. This allows a reader to retrieve one fact without knowing which chapter holds it.
Before Writing: Prepare the Manuscript
Page numbers must be final before indexing begins. Any change in layout after the index is compiled will shift locators and introduce errors. For this reason, indexing is normally the last editorial task, carried out on typeset pages or on a manuscript with embedded tags that update automatically.
The writer should also confirm the intended audience and the publisher's requirements. A scholarly monograph calls for dense, detailed entries, while a general interest title needs a shorter and simpler index. Publishers often set a maximum length, and many follow Chicago Manual of Style conventions.
Step 1: Read the Text as a Reader Would
The first pass is a full read with no entries written yet. The aim is to understand the scope of the book, its vocabulary and the questions a reader is likely to bring to it. Indexers working on technical titles often read a chapter or two before marking anything, so that the terminology becomes familiar.
Step 2: Mark Entries While Reading
On the second pass, each significant name, topic or concept is marked with its page number. Substantive discussion qualifies for an entry, while a passing mention does not. A reader who follows a locator to a single throwaway sentence will stop trusting the index.
Headings should be phrased as nouns or short noun phrases that a reader would search for. An entry for "indexing process" works better than "how to create an index," because the keyword leads and can be found alphabetically. Word processors offer a mark-entry function, but it records only what the writer selects, so the selection itself still depends on human judgement.
Step 3: Choose Strong Main Headings
Headings are often the hardest part of the job. The table below contrasts weak headings with stronger alternatives.
| Weak heading | Stronger heading | Reason |
|---|---|---|
| Things to avoid | Errors, common | Keyword placed first |
| Importance of planning | Planning | Noun phrase, alphabetically findable |
| General issues | (remove) | Too vague to locate anything |
| Management, project and Project management | Project management, with a cross-reference | Prevents duplicated, split entries |
Inverted headings let a reader find an idea under either of the terms they might try. For example, an entry for "project management" can be supported by a cross-reference from "management, project."
Step 4: Add Subentries Where Needed
An entry with a long string of page numbers should be divided into subentries. Chicago style suggests this once an entry carries more than five or six locators. Subentries tell the reader what each page contains, which saves them from testing every number in the list.
Budgeting, 22, 57
contingency funds, 61
forecasting, 58, 64
software tools, 70Subentries are listed alphabetically, with leading articles and prepositions ignored. They should not follow the order of appearance in the text.
Step 5: Record Locators Accurately
Locators are normally page numbers, though some books use paragraph or section numbers. A discussion spanning several pages takes a page range, such as 112 to 118, and publishers differ on how to abbreviate such ranges. Footnote and endnote references are marked with an "n" after the page number, as in 45n3, in many style guides.
Accuracy matters more than any other quality in this step. A single wrong locator damages the credibility of every correct one.
Step 6: Build Cross-References
Cross-references connect terms and prevent dead ends. A "See" reference redirects the reader from an unused term to the term the index actually uses, while "See also" points to related headings that might interest them.
Farm waste. See Agricultural runoff
Agricultural runoff, 88, 120
See also Water qualityEvery cross-reference must lead to an entry that exists. Checking this at the end is a standard editing task.
Step 7: Alphabetise and Apply the Book Index Format
Two systems of alphabetising are in use. The word-by-word system treats spaces as a break and places "New York" before "Newark," whereas the letter-by-letter system ignores spaces and reverses that order. The Chicago Manual of Style prefers the letter-by-letter method, and so do many university presses.
Formatting follows from the publisher's style sheet. Common instructions include a single column, hanging indents for runover lines and consistent punctuation between headings, subentries and locators. The indented layout places each subentry on its own line, while the run-in layout joins them in one paragraph with semicolons.
Step 8: Edit the Index as a Whole
The final pass treats the index as a finished document rather than a list of notes. The editor deletes trivial references, merges duplicate headings, adds subentries where a heading has grown long and checks that cross-references resolve. Coverage should be even across the book, so that a chapter near the end receives the same attention as one near the front.
Reading the index aloud from the perspective of a first-time reader helps expose gaps. If a likely search term leads nowhere, an entry or a cross-reference is missing.
Tools Worth Considering
Dedicated indexing software handles sorting, formatting and cross-reference checks, which allows the writer to focus on content. Word processors can generate an index from marked terms, though the output usually needs heavy editing. According to Johns Hopkins University Press, an index cannot be made automatically by Word or any other program.
For ebooks, an embedded index adds hidden codes to the text so that each page reference becomes a live link. This work takes longer than a print index and is usually priced higher.
Should You Write the Index Yourself?
Authors who know the subject can write a competent index, but the task consumes time. Reedsy reports that Wiley estimates 25 to 37.5 hours for a 250-page book. Authors who are close to the text also tend to index in their own language rather than the reader's.
Professional indexers typically charge by the indexable page, and the Alliance of Independent Authors cites average rates between $3.50 and $5.50. Hiring one makes sense for long, technical or commercially important titles. A short guide with a simple structure is a reasonable candidate for a first attempt by the author.