I've been installing the content that comes with Poser 11, plus a few things I purchased from the website. I go to the Materials list, click the little bundle of books with the plus sign and navigate to the runtime folder that belongs to what I am installing. It installs, but when it's done, a large number of them list the item, but show a [0] at the end. Sure enough, when I open the folder in Poser, there is zero in it. Other times it will slow a 1 or 2, and there will be 1 or 2 folders inside, with many items within those folders. But the ones that I install that show zero do not work at all, as no items appear after the title of the material I installed. Can anyone help me?

Linking a runtime folder to the library installs all the categories, not just one as you are describing.  The Materials may be associated with MATPose files usually found under the Pose category Tab.  To better convey some of the issues you are having, you can post screencaps of your Library, browser, ZIP program, etc.  

When I view my library, many of the categories show a [0] and sure enough, upon checking the folder breakdown, there are no items contained in them. Some of these came with Poser, so I was surprised to discover them empty. Others are purchases which are also empty. When I unzipped the files and examined them, there is content there, and when I selected the appropriate runtime, Poser seemed to be installing something. When I tried to reinstall, it says it is already installed, yet continues to show only the [0] and no items under that category. I would estimate that about 2/3 of the content is showing, whether it came with Poser or was added on and properly unzipped and installed. My computer exceeds the requirements to operate Poser and so I'm stumped as to what more I can do.

It looks like you have unzipped each of the content folders into its own runtime and added them each as an external library. The name of the runtime will appear in each of the content categories (character, pose, face, etc), regardless of whether there are items of that type in the runtime. 

Going on that assumption, the screen cap you show above shows that you have the character library selected. You'll notice that the first five legacy content packs have sometihng in the character library. But when you get to the sixth, it is a hair runtime and the associated content will appear under the Hair category.

Going further down, the 07 runtime has clothes in it. Because it is showing 0 in the character library, you will probably find the clothing in the Props library for that one.

You haven't done anything wrong here, it's just how Poser works.

Thank you for that explanation. However, some of the folders don't have content no matter which library I select. For example, I purchased clothing from LF Punk and the first folder shows at the bottom of my screen cap. But even in the clothing library, it shows zero, despite the fact that the runtime was installed and files were present after I unzipped the file. Some of the content always shows zero, regardless of the library I am viewing it under.

Going back to  your first sentence, you are saying there would have been a better way to install these so that things would perhaps appear more organized? I used the image of the books with the plus sign to add each runtime. Is there a different/better way to add them?

What I did was combine them all into a single runtime named Poser 11 Included.

Each of those individual zips has a Runtime folder in it. Just drag and drop that Runtime folder into whatever you want to name your "combined" folder. Add the combined folder to Poser as an external library, and then  you can remove all the individual ones.

After it's all combined into a single runtime it will look more like this:

Thank you. I will absolutely give that a try!

Whatever you do, don't install those runtime folders into your Primary Poser runtime.  That will cause a different type of problem that becomes more difficult to resolve.

Ok, thanks for the advice. I'll follow your original suggestion and make a folder.

Yes good point hborre. The "Poser 11 Included" runtime that I have was created on my D drive and is entirely separate from the content that was installed with Poser 11.

I was able to uninstall, then correctly reinstall these from the zip files. Originally, I had manually unzipped all of the folders, and just added each 'runtime' folder, but letting Poser unzip them seemed to make things more organized. Thanks to everyone who helped me! :)