You can export constituent contact information via an Advanced List, then use the Import option in Google Contacts to import your data. 

To create an Advanced List:
  1. Start from any capability, go to Analysis > Manage Lists
  2. Click the Manage Basic and Advanced Lists block under List Actions
  3. Click the List Templates tab at the top.
  4. From the Template Category drop down, select Constituent Information.
  5. You can use any of these lists to export, as well as Copy one of these templates to export your information.
  6. Once exported, you will want to save this list as a CSV file, as Google Contacts supports CSV files or vCard files.
  7. You can then go into Google Contacts > Import Contacts > and click Choose File > Import to import your contacts.

Also see  Advanced Lists for Beginners [PDF].