Fortunately, it's easy to, just about literally, drag them along and import all Address Book contacts (including groups) into Outlook for Mac.
Import Mac OS X Address Book Contacts into Outlook for Mac
To import your contacts from Mac OS X Address Book into Outlook for Mac:
- Open Address Book.
- Drag and drop All Contacts from the Group list to your Desktop.
- Close Address Book.
- Open Outlook for Mac.
- Select View | Go To | Contacts from the menu.
- Drag and drop "All Contacts.vcf" from the Desktop (created before) to the Address Book root category.
- Make sure a + appears as you hover the file over the Address Book category.
- Delete the "All Contacts.vcf" file from your Desktop.
Outlook for Mac will automatically create and assign categories if you have your Address Book contacts in groups.