re :''In Address Book, I exported (cvs file) Personal and Collected Address Books. On new computer Address Book, I imported those files. Now I have a filled Personal Address Book and a second, empty Personal Address Book. Same with Collected Addresses. '' When you imported them, they were added as address books you created. But because you did not change the 'Name' of the .cvs file, it used that unchanged name as the address book, thus you would appear to have address books with same name. The blank ones are the default address books that cannot be deleted. '''Option 1:''' Suggest you rename the address books you imported. * Right click on address book and select 'Properties'. * This will allow you to rename an imported address book. * click on OK '''Option 2:''' If you still have old computer, you can copy the 'abook.mab' (Personal Address Book) and 'history.mab' (Collected Addresses) files and paste them into the new computer replacing the empty default ones. How to do this ? On old computer : Thunderbird must not be running. Access the profile folders. The default location on Windows OS is: * C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\ The 'profile name' is usually called xxxxxxxx.default, where the x's are letters and numbers. Copy the 'abook.mab' and the 'history.mab' files to a usb. On new computer : Thunderbird must not be running. Access the profile folders. The default location on Windows OS is: * C:\Users\<Windows user name>\AppData\Roaming\Thunderbird\Profiles\<Profile name>\ The 'profile name' is usually called xxxxxxxx.default, where the x's are letters and numbers. * Delete the 'abook.mab' file and the 'history.mab' file. These will be empty default address books. * Paste in the copied 'abook.mab' and the 'history.mab' files that are on the usb, to replace the deleted ones. * You will also see additional address book that you imported, they are likely to be called eg: 'abook-1.mab'. They will have that additional number in the name. These are the ones you imported, so you can delete them because you have copied over the originals. Now start Thunderbird. Example image showing contents of a profile name folder.