Tags are presently not shared. In other words, the tag structure of a shared notebook does not proliferate or become suddenly useable within your own tag framework. For good reason, too. You wouldn't want a carefully manicured tag structure upended by someone else's shared notebook. We're working on ways to make tags more useful between sharers, though. I know you are trying to protect us from other people but if all notebooks were treated the same but we were able to put shared notebooks inside a stack then we could choose if we wanted a mangled mess or not. You could start off by saying all users have two stacks, Personal Notebooks Stack and Shared Notebooks Stack. If we chose to put a shared notebook in our stack then we have chose to take their mess. (The main people I want to share with are my wife and my dad, so I trust them with their tag making ability.) If I want to see my carefully carefully manicured tag structure, then I'll choose my Personal Notebooks Stack. If I want to find the information by tag no matter what notebook it's in, then I'd choose All Notes. Instead of using stacks, you could just expand the current "All Notes" to be "All Notes" and "All Personal Notes".