TinyPortal

Is there a way to control permission for which groups can view articles? Can I prevent guests from viewing articles?

As an article I don't think that there is, but there are other options. You can put the article in a block and will have the usergroup options for the block. For accessing a list of articles you could make html or css menus in blocks (not the menu block as you can only have one) and set the block membergroups.

Great! That will do nicely. Maybe even better.  :D

I can have one block that shows the content I want for those logged in, and another block that shows different content for guests telling them they need to log in and what they'll get if they do.