i have several avery labels but can't find them in word. why aren't all avery labels supported in word?

The answers posted here so far are good, but they don't address some more basic issues. Yes, Avery publishes two or more products that have the same dimensions—if I don't see the exact number I need, I can often find a suitable replacement. Yes, I can download the label template I need from Avery.com. Yes, when all else fails, I can create my own template. However, I'm curious why the label wizards in Word for PC and Word for Mac differ dramatically. The PC version is far more robust. I'll illustrate with Avery label number 5286 (comparable: 5453). Two significant points: (1) Both product numbers appear in the label wizard on the PC, but neither appears in Word 2011; (2) Avery's downloadable template 5453 for Word for PC differs significantly from the same template for Mac.

My primary computer is a MacBook Pro (OS X 10.8.4). I also have a Windows 7 PC. I subscribe to Microsoft Office 365 on both machines. My Mac uses Office 2011.

I have downloaded from Avery their template for label 5453 [two 3" X 4" labels per 4" X 6" page] on both machines. My first download was for the Mac, and I was rather perplexed by some features. Only after long discussions with other users did I find that the Mac version of this template has two rectangular shapes lying on top of the table cells that separate the two labels on each sheet. Further, I see two large "I-bars" parked in the center of each label. 

Neither of these features show up in the 5453 template for Windows PCs. The PC version gives me exactly what I expect: two simple table cells. I feel those shapes in the Mac version—that match exactly the size and shape of the table cells—are unnecessary and confusing.

I'm quite familiar with the envelopes and labels wizard. Both template numbers 5286 and 5453 (essentially identical templates) appear in the spin box in the label wizard in the Windows version. Neither template appears in the label wizard in Word 2011. In fact, the only label templates that do appear are for Avery products that come in page size 8.5" X 11". There's nothing for products with page size 4" X 6".

Did the Microsoft design team for Office 2011 for the Mac chose to limit the number of Avery label templates to display in the label wizard? Did they assume that Mac users are more interested in the artsy stuff—pictures and music—such that word processing is just a side-show? I don't mean to sound harsh. I really do like Word 2011, but the labels wizard in Word for PC is remarkably more robust. I'm curious why that is so.

Is there a way for a mere mortal to add content to the label wizard, or is that a job for the uebergeeks?

Daniel's observation is pretty much on target... The software doesn't store individual template file for the labels listed in the window. The specs for them are stored as a database & new label documents are built based on those specs. As a result, you cannot add additional templates to the database because there are none to begin with.

You do have 2 options:

1. Save an actual template file just as you've already done. This method does not add to the List of Products in the Labels dialog, or
2. Use the New Label design tools to create a custom label with the name you choose. Your custom labels are entered into the database & added at the beginning of the List of Products being viewed at the time the custom label specs are saved.

IMO he's right [at least in large part] about the differences in the feature set -- Simple economics, although a number of other constraints factor in.

You can use another label having the same size. Click the Options button and look for a suitable replacement.

You can also define your own label and give it the same name as the missing label (Tools > Labels > Option > New label).