It can drive you bonkers
Headline-style capping (sometimes called title caps, title case, or billboard-style capping) is often applied to major signposts in text. The titles of books, for example, and the chapters and sections within.
The use of headline-style capping is not as widespread as once it was. European publications led the way with sentence-style capping, and more recently, publications in this country have followed suit. Newspapers, journals, magazines, and published books have in recent years turned more and more to sentence-style caps.
But for those circumstances where this style does apply, here’s a summary of the typical approach. Some aspects (particularly the treatment of prepositions) vary by context.
What’s capped, what’s not
Words capped by part of speech
Cap all words of “substance.” That is, cap all words that fall into the primary parts of speech, words that confer meaning in a phrase —
Nouns
Pronouns
Adjectives
Adverbs
Verbs
Cap these words regardless of length. Sometimes, they are short words. Am, Are, and Is, for example, are verbs and so they’d all be capped. The pronouns It and Its are capped.
Note that subordinating conjunctions (Because, Although, While, When, If, and so on) are adverbs, meaning that they’re also capped.
Special case: Prepositions
Here is where guidelines often differ. In an academic environment, all prepositions are down, regardless of length. In trade publishing, prepositions of four or more letters — or sometimes of five or more letters — are most often capped.
Words capped by design
Cap words in these special categories —
The second word in a hyphenated compound if it would take a cap on its own (if, in other words, it’s not a short preposition): for example, the second word in Red-Haired, but not the second word in Break-in
Any word following a colon, regardless of part of speech
Any word beginning or ending the entire phrase, regardless of part of speech
The particle in a phrasal verb: for example, Ask Around, Break Down, Break In
Yes! If you are using headline-style capping, the second word in hyphenated compound nouns like break-in or break-up would be treated one way and the second word in phrasal verbs like break in or break up, another.
Like this:
In Which Our Heroes Break In to Save the Day
Breaking Up Is Hard to Do
A Massive Break-in Ruins the Day
The Break-up That Wasn’t
Preposition and Particles
Prepositions precede, and govern, nouns. (Like this: in the field, on the table, around the house.)
Particles are a special category of preposition or adverb only when they are currently functioning to complete the sense of a verb, which means that in this case they are an integral part of that verb. (Like this: ask around, add up to, break down, break up, look down on.)
Not all two-word or three-word verb phrases are bona fide phrasal verbs. Sometimes the phrase is just a verb + an adverb.
This is a relatively small point, one you may never run into. If you do, your copyeditor should sort it for you.
Words not capped
Do not cap any of these words (unless, naturally, it is the first word, the last word, or the first word directly following a colon) —
Articles (a, an, the)
Coordinating conjunctions (and, but, or/not, for, yet, so)
The infinitive marker (to)
Prepositions:
All prepositions (if following academic guidelines)
Prepositions of four or fewer letters (if following one of the common alternative styles), meaning words like at, by, for, in, into, of, on, to, with, to name a few
And do not cap any special terms that always, even when starting a sentence, remain lowercase.
The treatment of some common words
Words always capped, never capped, and sometimes capped. Remember, though, that position trumps all other guidelines: the first word, the last word, and the first word following a colon are always capped.
Cap these words
Some of the words in this list are subordinating conjunctions. Some are relative pronouns and adverbs. Some are coordinating adverbs. Some are prepositions of five or more letters. A few are regular adjectives, adverbs, nouns, pronouns, or verbs. Some cross boundaries and may be used in different ways.
If you’re writing in an environment that keeps all prepositions down regardless of length, then YMWV.
About
Above
After
All
Although
Also
Among
Are
As (as an adverb or a subordinating conjunction)
As If
Be
Because
Before
Below
Besides
Between
Even
Even If
Even Though
How
If
In Case That
In Order That
In That
Indeed
Instead
Is
It
Its
It’s
Once
Our
Rather Than
Since
Still
So That
Than
That
Their
Then
These
This
Though
Those
Til (as a subordinating conjunction)
Toward
Under
Unless
Until
Was
Were
What
Whatever
When
Whenever
Where
Wherever
Whereas
Whether
Which
Whichever
While
Who, Whose, Whom
Whoever
Why
Within
Without
You
Your
Do not cap these words
Three of the words in this list are articles; six are coordinating conjunctions. The rest are prepositions of four or fewer letters.
This is not an exhaustive list. Just some of the more common confusions.
a
an
and
as (as a preposition)
at
but
by
for
from
into
nor
of
onto
or
over
so
the
till (as a preposition)
to
upon
with
yet
Exception: If one of these words happens to fall into one of the three special positions (first word, last word, first word following a colon), do cap it.
Sometimes cap these words
These words can function either as particles, to complete a verb phrase, or as prepositions, governing a noun and setting up its relationship in the sentence.
Cap them when they function as part of a phrasal verb (as in, Break It Off). Do not cap them when they function as prepositions, that is, positioned in front of a noun phrase.
This is not an exhaustive list. Just some of the more common confusions.
in
off
on
out
up
Exception: If one of these words happens to fall into one of the three special positions (first word, last word, first word following a colon), do cap it.