I just set up my new Macbook Pro Retina, I want to bring in the contacts from the imac Address Book. How do I do this?
When you first boot up the new machine, you'll be prompted to transfer the data from another computer or its backups as part of the setup process. That's the best way to do it.
If you chose not to migrate your account over as Linc suggested, export the Contacts from the iMac Address Book to an Address Book archive. Copy the file over to your new Mac and double-click the file. It will ask if you want to replace the contents of your Contacts with the backup.
If the iMac is using Tiger or earlier, export the contacts as vCards (it will be just one file), and do the same as I stated for the archive.
importing Address Book contacts
