The Massachusetts Association of Realtors legal hotline answers a question about emotional support animals and condos rules …
Q: Can a Condominium Association deny a prospective Buyer’s emotional support animal because the Rules and Regulations state, “No pets of any kind?”
A: No. Under the federal Fair Housing Act and Massachusetts law, emotional support animals (ESAs) are considered assistance animals, not pets. Condominium Associations must provide reasonable accommodations for a Buyer with a disability who requires such an animal, even when the Association has a “no pets” policy. Failure to comply may constitute housing discrimination.
Unlike a service animal, an ESA is not required to have specialized training to perform specific tasks for its Owner. An ESA is an animal that provides a mentally therapeutic benefit to its Owner.
The Association can request a letter from a licensed healthcare provider confirming that the Buyer has a disability and requires the particular animal for his emotional health. The Association cannot, however, request the Buyer’s health records or demand disclosure of the particular type of disability.
For a detailed review of ESAs in Massachusetts housing:

