In California, an Emotional Support Animal (ESA) Letter is a legally recognized document issued by a licensed mental health professional, certifying an individual's need for an ESA to support their emotional or mental well-being. This letter grants certain protections, including housing rights under the Fair Housing Act, allowing individuals to live with their ESA even in housing that restricts pets. California law also outlines specific guidelines to ensure the legitimacy of ESA letters, requiring that licensed providers have a legitimate therapeutic relationship with the individual seeking the letter.