If you call this method with an empty string, it will return a list of all locales available in the ICU library (via the intl extension):<?phpprint_r(ResourceBundle::getLocales('')); /* Output might show * Array * ( * [0] => af * [1] => af_NA * [2] => af_ZA * [3] => am * [4] => am_ET * [5] => ar * [6] => ar_AE * [7] => ar_BH * [8] => ar_DZ * [9] => ar_EG * [10] => ar_IQ * ... */?>