It’s driving me nuts. I type in IN for Indiana and press tab, and “Indiana” appears!
There seems to be no way of turning this off. I looked through all the menus; I looked through Address Book help–nada.
Please assist if you can–I want to turn this useless, &%$!@ function OFF!
Thanks. 
Not sure how to turn auto-complete off, but if you type "IN <spacebar> <tab> you should get “IN”. “IN” and “Indiana” should now be in your dropdowns.
Yes, this kind of thing works, but it is horribly easy to hit a key and have it insert something you don’t want. Bleh–I expect better from Apple.
Be a 6 time champ–save me from this curse!
Mac experts?!
In Safari’s Preferences, click on AutoFill, you can turn off this feature there.
Seems like the offending application has to be told not to do this, instead of telling Address Book not to share the info with other apps.
That didn’t work either, sadly.
HELP!
Surely someone knows how?
Where are the Mac experts?!
If the software doesn’t support disabling Autocomplete, no amount of expert pontification will help you.
Then I just need an expert to tell me disabling it is impossible, and that will be that.
After you type “IN,” press “Return” before it has a chance to autofill. It will enter the text as you want it and take you to the next field just the way “Tab” does.
Good potential with this program, but not up to Apple standard.