Question: We currently use UPPERCASE headers and titles quite a bit (probably too much) and are looking to adopt a consistent set of rules for when it makes sense to use...

* **ALL UPPERCASE**
* **C**apitalize the first word
* **C**apitalize **E**ach **W**ord.

I was hoping to find one simple generic rule that covers everything but haven't found it yet. I've found plenty of information regarding why I should [never use uppercase ever](http://antezeta.com/news/about-all-caps) because [IT LOOKS TERRIBLE](https://ux.stackexchange.com/questions/11043/all-capital-titles-good-or-bad/11053#11053) but that's not what this question is about.

---

My question specifically revolves around text for things like:

* **labels** "Sort by:" or "Sort By:"
* **tooltips** "Primary address" or "Primary Address"
* **buttons** "Delete user", "Delete User", or "DELETE USER"
* **navigation** "HOME" or "Home"
* **breadcrumbs** "HOME > MANAGE GROUPS", "Home > Manage Groups", "Home > Manage groups"

Answer: 
I researched the site with the most unique visitors to see if I could find a consistent pattern.

**1. Facebook uses ALL UPPERCASE rarely in place of column header rectangles**

![headers](https://i.stack.imgur.com/7u02u.png)

**2. Facebook capitalizes only the first letter of all the words in a field label**

![field labels](https://i.stack.imgur.com/RFm2r.png)

**3. Facebook capitalizes the first letter of *important* words**

In almost all cases where a full sentence isn't used Facebook uses the Titles of Works pattern -- `Mark All as Read`, `News Feed Preferences`, `Log Out`, `Report a Problem`, ...

![top links](https://i.stack.imgur.com/9eWbZ.png)

![menu items](https://i.stack.imgur.com/QiRaL.png)

Here is a summary of the general rules that Facebook appears to follow in most cases:

> 
> * Capitalize the first and the last word.
> * Capitalize nouns, pronouns, adjectives, verbs, adverbs, and subordinate conjunctions.
> * Lowercase articles (a, an, the), coordinating conjunctions (and, or), and prepositions (of, by, in).
> * Lowercase the infinitive "to".
> 
> 
> 

Source: *The Chicago Manual of Style*: 16 ed. [paragraph 8.155 Titles of Works](http://www.chicagomanualofstyle.org/16/ch08/ch08_toc.html)
The reason for specific typographic styles (ALL CAPS, Some words Caps, etc...) with regards to heading, title, button, breadcrumbs, and other related materials is due to the mandates of the manual of style that the organization is using.

As Dave references, the Chicago Manual of Style is one of the most popular reference tools as they have been around for a long time and have a very well developed ruleset on how to set text. There are others as well as APA, or NASA. Microsoft even has a manual of style that is more geared towards technical terms and items.

That's not to say that you should be using one of these, but you should either find one, or create one and then stick to that as it will make all of your typesetting uniform and predicable across your company.