1 The rule in plain terms
The rule is straightforward: subheads and decks take sentence-style capitalization and no end punctuation. That means you capitalize only the first word and any proper nouns, just as you would in a normal sentence. A subhead like 'City council approves new budget' is correct; 'City Council Approves New Budget' is not. The same goes for decks, which are the summary lines that often sit beneath a headline. They should read as a single, clean phrase or sentence fragment, not a title. If a deck is a full sentence, it still avoids a period unless it is a question. The goal is visual and grammatical consistency across the publication. When every subhead and deck follows the same pattern, readers absorb the structure without noticing the mechanics. That is the quiet work of a copy desk: making the scaffolding invisible so the story itself can do its job. This rule applies to both print and digital formats, and it holds whether the subhead is a single word or a longer phrase. The only variation is for questions, which take a question mark, and for proper nouns, which keep their capitals.
2 Why editors enforce it
Editors enforce this rule because consistency signals professionalism and care. When subheads and decks are styled haphazardly, readers may not consciously notice, but they feel the friction. A deck in title case next to a subhead in sentence case looks like two different publications stitched together. That kind of inconsistency erodes trust in the copy and, by extension, in the reporting. The rule also aids comprehension. Sentence-style capitalization is easier to read quickly because it mimics the natural flow of prose. Title case, by contrast, forces the eye to stop at every capitalized word, which slows scanning. For a reader moving through a long story, subheads act as signposts. If those signposts are styled uniformly, they guide the reader smoothly. If they are not, they become speed bumps. Editors also enforce the rule to save time in production. A single style for subheads and decks means fewer queries, fewer corrections, and a faster path from draft to publication. Finally, the rule reinforces the publication's voice. A consistent style is part of a brand's identity, and readers come to expect it.
3 Where writers usually slip
Writers most often slip by defaulting to title case. It is a common habit from academic writing, where headings are often capitalized, or from other publications that use title case for subheads. Without a conscious check, a writer will type 'How to Improve Your Writing' instead of 'How to improve your writing.' Another frequent error is adding a period at the end of a deck or subhead. Writers see a complete sentence and instinctively punctuate it. But subheads and decks are not sentences in the traditional sense; they are labels. A third slip is inconsistency within the same story. A writer might use sentence case for one subhead and title case for the next, especially if they are copying from different sources or drafting quickly. A fourth error is making the subhead too long or too vague. A subhead that says 'Important information about the new policy' is both wordy and uninformative. It should be specific: 'New policy changes overtime rules.' Finally, writers sometimes forget that proper nouns still need capitals. They might write 'new york' instead of 'New York' in an attempt to follow sentence case too rigidly. The rule is not about lowercasing everything; it is about capitalizing only what grammar requires.
4 Applying the rule on deadline
On deadline, the fastest way to apply the rule is to write the subhead or deck as you would a normal sentence, then strip the period and check the capitalization. Start with a capital letter, lowercase everything else except proper nouns. If you are unsure whether a word is a proper noun, check the AP Stylebook or the publication's own style guide. For decks, keep them to one line if possible. A deck that wraps to two or three lines loses its punch and can look cluttered. If you must write a longer deck, treat it as a single sentence fragment and avoid internal punctuation like semicolons or dashes unless absolutely necessary. When you are editing someone else's copy, do a quick pass specifically for subheads and decks. It is easy to focus on the body and miss these elements. A simple find-and-replace for periods at the end of subheads can catch many errors, but be careful not to remove periods from sentences within the body. In a pinch, read the subhead aloud. If it sounds like a headline shouted in all caps, it is probably in title case. If it sounds like a calm statement, it is likely correct. Speed comes from repetition; the more you apply the rule, the more automatic it becomes.
5 Legitimate exceptions
There are a few legitimate exceptions to the rule. The most common is the question subhead or deck. If the subhead is a direct question, it should end with a question mark. For example, 'What happens next?' is correct, even though it has end punctuation. The capitalization rule still applies: capitalize only the first word and proper nouns. Another exception is when a subhead or deck includes a proper noun that is normally capitalized, such as a person's name, a place, or a formal title. Those words keep their capitals. For instance, 'Mayor Jane Smith announces plan' is correct. A third exception is when the subhead or deck is a direct quotation. In that case, follow the normal rules for quoting: capitalize the first word of the quotation and use quotation marks. However, if the quotation is a full sentence, it may end with a period inside the quotation marks. This is rare in subheads but can happen in decks. Finally, some publications use title case for decks as a deliberate style choice. If your publication's style guide says otherwise, follow it. The rule described here is the AP standard, but house style always wins. The key is to be consistent within the publication, not to impose one rule everywhere.
6 A worked example from the copy desk
Imagine a reporter files a story about a new city policy on sidewalk repairs. The headline is 'City to fix sidewalks.' The reporter's draft deck reads: 'New Program Will Address Years of Complaints.' The subheads in the story are: 'The Problem With Current Sidewalks,' 'How the New Program Works,' and 'What Residents Can Expect.' A copy editor sees three issues. First, the deck is in title case and has a period. Second, the subheads are also in title case. Third, the subheads are a bit vague. The editor revises the deck to: 'New program will address years of complaints' — sentence case, no period. The subheads become: 'The problem with current sidewalks,' 'How the new program works,' and 'What residents can expect.' Note that 'residents' is not capitalized because it is not a proper noun. The editor also checks that each subhead is specific enough. 'The problem with current sidewalks' could be more precise, but it works as a signpost. If the story were about a specific neighborhood, the editor might write 'The problem in Elmwood' to be more concrete. The editor then scans the rest of the story for consistency. This example shows how a few small edits bring the story into line with house style and make it easier to read. It also shows that the rule is not about being rigid for its own sake; it is about clarity and consistency.
7 Quick reference and related rules
For quick reference, remember: subheads and decks use sentence case, no period at the end, except for questions. Capitalize only the first word and proper nouns. Keep them concise and specific. Related rules include headline style, which typically uses sentence case as well, though some publications use title case for headlines. Always check your publication's style guide. Another related rule is the use of colons in subheads. If a subhead has a colon, capitalize the first word after the colon only if it is a proper noun or the start of a complete sentence. For example, 'New policy: What it means for you' is correct; 'New policy: what it means for you' is also correct if 'what' is not a proper noun. But 'New policy: Mayor Smith responds' capitalizes 'Mayor' because it is a title. Also, avoid using all caps for subheads unless it is a deliberate design choice. All caps can be harder to read and may come across as shouting. Finally, ensure that subheads and decks are not redundant with the headline. They should add new information or provide a different angle. A deck that simply repeats the headline wastes space. Use these elements to guide the reader and enhance the story's structure.