What to Capitalize in a Title: APA Title Capitalization Rules

Which words do you capitalize in a title?

Have you ever been confused about which words to capitalize in the title of your manuscript? You have probably seen titles where only the first word is capitalized (so-called “sentence case”), titles where all words seem to be capitalized (“title case”), and also titles that look like combinations of the two. And you might have wondered where there is any general rule to all this. 

The answer is that, no, there is not really one general capitalization rule, but there are several style-dependent capitalization guidelines you can rely on, and the journal you plan to submit to will tell you (in their author instructions) which one they want you to apply to your manuscript before submission. Just like you format your manuscript and reference list following APA or MLA formatting rules, you apply the respective style guide to capitalize your title, headings, and subheadings. In this article, we will first explain the general rules on what types of words to capitalize (e.g., nouns, articles, and conjunctions) and then look at the APA and MLA style guides in particular and their specific variations of those rules.

Research Paper Title Capitalization Rules

According to most style guides, all proper nouns, pronouns, verbs, adjectives, and adverbs in titles of books and articles are to be capitalized. Some elements of titles are, however, never capitalized, such as articles (except articles at the beginning of a title), and some, such as conjunctions, can or cannot be capitalized, depending on the specific style guide variation. In the following, we will outline the general rules for all the different words in your title so that you can orient yourself easily to the different style guides and adapt your title quickly when necessary. 

Capitalizing Nouns and Pronouns in Titles

Nouns (including formal names of people, organizations, and places) and pronouns are easy to format, as all style guides agree that they should always be capitalized using title case capitalization. 

Capitalizing Articles in Titles

The rules for articles are also simple, as all major style guides agree that articles should be lowercase in titles—unless they represent the first and/or last word in the title:

In the latter example, the first “the” is capitalized because it is the first word of the title, while the second “the” is lowercase as articles usually are. Note that the same rule regarding article capitalization applies to subtitles as well.

Capitalizing Conjunctions in Titles

Conjunctions are a slightly more complicated case, as style guides differ on whether to capitalize them or on which conjunctions to capitalize. According to some guides,  conjunctions of three letters or fewer are to be written in lowercase while longer ones should be capitalized. Other style guides, however, state to write all conjunctions in lowercase, or make exceptions for specific conjunctions such as “yet”, “so”, and “as”. It is therefore always necessary to look up the specific rules of the target journal before submitting a manuscript—and have a look at our sections on APA and MLA style below. The following examples are, however, fairly universal:

Capitalizing Prepositions in Titles

Capitalization rules for prepositions are equally ambiguous and depend on the specific style guide you follow. Prepositions of four letters or more are often capitalized, while according to some style guides, all prepositions are written in lowercase, no matter their length. Sometimes, for example, when following the Chicago Manual of Style, capitalization depends on how a preposition is used in a title and whether it does indeed function as a preposition. According to this rule, prepositions are capitalized when they are used “adverbially or adjectivally” in prepositional phrases (as in “How to Back Up a Computer”), but not when used otherwise.

Capitalizing Adjectives and Adverbs in Titles     

Rules for capitalizing adjectives and adverbs, like nouns, are unproblematic, as they are capitalized across style guides. 

Capitalizing Verbs in Titles      

Verbs are another easy case and are also always capitalized, according to all style guides. 

Title Case Rules by Style Guide

APA Title Case Rules   

APA (American Psychological Association) style is most commonly used for scholarly articles in the behavioral and social sciences. The APA guidelines on when to capitalize a title include the following rules:

MLA Title Case Rules  

The Modern Language Association (MLA) Handbook, used primarily to write papers and cite sources within the liberal arts and humanities, promotes the following rules for when to capitalize a title or header:

Additional Rules for Title Capitalization 

As we have stressed several times throughout this article, it is crucial to always check the specific rules of the target journal and/or the rules of the style guide the target journal wants you to follow—note that these can sometimes conflict with each other, in which case the journal rules override the style guide. Apart from the two common style guides we explained here, APA and MLA, there are several others that have their own rules, such as the Chicago Manual of Style, the American Medical Association (AMA) Manual of Style, or the Associated Press Stylebook, an American English grammar style and usage guide originally developed for AP writers but now used widely across journalistic fields. There is even a specific set of rules for the capitalization of titles of Wikipedia articles!

One capitalization rule that might not necessarily be mentioned in such style guides but is relevant for some academic/scientific fields is that when the Latin name of a species is mentioned, the second portion of the name must be written in lowercase, even when the rest of the title follows title case rules.

Another capitalization rule you might need when describing research experiments is that both elements of spelled-out numbers or simple fractions should be capitalized in title case:

Lastly, no matter your personal preference, make sure you always write the titles of books and articles exactly as they are written on the original document/in the original version, even if they do not seem to follow common capitalization rules.

Correct Capitalization in Your Title with Professional Editing   

If you are even more unsure now how to capitalize your title or find the author instructions of your target journal confusing (which can happen, since those sets of rules have often grown organically over a long period of time and, as a result, can lack consistency), then you might want to make use of professional English proofreading services, including paper editing services—your professional academic editor will figure such details out for you and make sure your manuscript is in the correct format before submission.

If you need more input on how to write and perfect the other parts of your manuscript, then head over to the Wordvice academic resources website where we have many more resources for you.

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