Many ESA owners register their emotional support animals in order to get a registration number and ID card for their ESA. ESA owners always have the option of registering their ESAs, but registration and ID cards are not substitutes for obtaining an ESA letter. An ESA letter is essential if you want to officially qualify for an emotional support animal. Registering an ESA provides additional peace of mind and convenience. Only ESA owners with valid ESA letters should register their emotional support animals in a database and obtain an ID Card (see below for more info about ESA letters).