To
Check Readability Levels in Word
Word XP
Tools
Spelling & Grammar
Before you run
anything, click on the Options
button at the bottom of the page.
Check the Show Readability statistics box
OK

Word 2007

Word Options
Proofing
Check the Show Readability Statistics box
Once this has been set, run Spell Check and the readability
will appear at the end of the document.