Smaller font, wider label, calculated field that contains X number of characters of the offending field are some options.
Here is the receipe I employed...
I went to the Mailing label layout which I had created with the New Layout/Report dialog.
Then I cleared the Body section of everything.
Then I added the fields I wanted to appear using the Field Control tool.
Truncation, which is what I wanted to take place, occurs if any field would breach its boundry.