Hi Jennifer, welcome aboard!
Guests traveling to the Bahamas and Caribbean with Disney Cruise Line can view the
Travel Document Information on Disney Cruise Line's website to ensure they have the most up to date information on what will be required.
For your Eastern Caribbean sailing you do not necessarily need a passport (a state issued driver's license and birth certificate will be fine), but if you have time and the ability to do so, I'd highly recommend getting passports. My family travels with our passports, even the kids, because we feel better knowing that if an emergency or health issue were to happen and we were not able to get back on the ship at one of the ports, we'd more easily be able to get home with our passports. We lock them in our stateroom safe during the cruise but always carry them with us in port.
Also, since passports are valid for quite a few years, even the kids' passports, we are ready to set sail on our next adventure. I promise that once you sail on this cruise with Disney you are going to want to do it again!
I hope that helps as you plan, Jennifer. Please let me know if you have further questions before you set sail!