I have some old documents that were formed in Claris on OS 9 on my new mac with OS X. When I try to open them, the computer uses adobe acrobat reader 5.0 which of course will not open them. A message comes up that it cannot be opened because it is not the supported file type or the file is corrupted. I've tried rebuilding my desktop, but to no avail. Help! I usually deal with windows and this is getting frustrating.

I've had some success opening very old Claris documents with TextEdit. Just do a 'get info' on a Claris document and change the 'open with' to TextEdit.

All the formatting is lost, plus you'll have a lot of gobbledygook, but all of your old text will be readable.

By "Claris document", do you mean a Claris Works document? If so, which version? AppleWorks might (should) be able to open those in OS X.

I've found that Appleworks running on OS X won't open documents I have from the early 90s which were created by early versions of Claris Works (can't remember which versions of Claris Works I used then). If I try to open them with AppleWorks I get an error message. Word won't open or translate them, and neither will MacLinkPlus. So I tried TextEdit and at least I managed to salvage the text.

AppleWorks 6 dropped support for older versions of AppleWorks/ClarisWorks

When converting an old CW doc, that usually can be opened in version 5 of AppleWorks. Save as a version 5, then the resulting file can be opened in version 6. Not a very pretty way to do that, but it works. Some of the file opening utilities could help, too.

But doesn't Appleworks 5 only run in OS 9? And 9 won't run on Intel Macs!

But doesn't Appleworks 5 only run in OS 9? And 9 won't run on Intel Macs!

Both true - but ver 5 will open much older documents, and ver 6 will not.
So, you open the doc with ver 5 (on an older Mac...) and save as a ver 5 document. That will give you a document that you can then open on the intel Mac. But you won't be able to do that document changing on your intel Mac.

There may be some other software that can read older ClarisWorks docs, but going through ver 5 should leave original formatting intact, as much as is possible.

MacLink Plus translates most Claris files to just about anything you want, IIRC.