If you don't see the Address Book columns (Group & Name columns) when you switch to Preview mode, there are two possible reasons:
Starting in OS X 10.7, Apple gives you, the user, more control over which applications are able to access the contact information in the Contacts application. If your contacts aren't appearing in Labelist, you may need to explicitly grant permission for Labelist to access to your contacts. Here's how:
1) Open System Preferences
2) Open the "Security & Privacy" preference pane
3) Select "Privacy" tab
4) Select "Contacts" in the sidebar on the left
5) On the right side, scroll down until you see Labelist
6) Select the check box next to Labelist to allow it to access your contacts
7) Quit and relaunch Labelist
The Address Book columns (Group & Name columns) only appear in PREVIEW mode when your design contains one or more DELIVERY fields. If your design does not contain one or more Delivery fields, then there isn't a reason for the Address Book columns to appear because there isn't any place on your design to put information from the Address Book.
Here's how to add some Delivery fields to your design and get the Address Book columns to appear:
1) Create or open an existing design
2) Switch to Design mode
3) Select the "Fields" tab on the right side of the window
4) Select the "Others" tab at the top of the Fields sidebar on the right side of the window. You'll see a list of DELIVERY fields. There are actually two different types of fields: Return address fields and Delivery address fields. Return address fields represent represent YOU. Delivery address fields represent the person in your Address Book that you're sending the label or envelope to. The Return address fields are listed under the "Me" tab, while the "Delivery" fields are listed under the "Others" tab.
5) Expand the "Delivery Address Blocks" section of fields. Address blocks contain a handy collection of fields already arranged for you like Name, Street Address, City, State, and Zip. An Address Block is a just a simply and quick way to get all of the basic fields on your design at once instead of dragging them on individually.
6) Drag the "Name" delivery address block on to your design.
7) Switch to Preview mode. You'll now see the Address Book columns
8) Select one or more contacts in your Address Book. A label or envelope will be created for each selected contact.