As a general matter, the law prohibits discrimination against the disabled in housing: so, for example, you cannot be evicted *because* your son is mentally ill. However, that does *not* mean you cannot be evicted for  other reasons. So, for example, if you have not paid rent, the landlord may certainly evict you, notwithstanding your son's mental illness; the landlord could also evict you for willfully causing damage to the premsis, for threats against the landlord, for disturbing the peace, or for other lease violations. (Though the requirements to evict for each reason, such as the amount of notice you would have to get, and whether you get a chance to correct the behavior, varies with each ground for eviction.) If you feel the eviction is either because of discrimination against your son or otherwise improper--e.g. you actually haven't violated the lease, you pay rent on time, etc.--you may have a defense to eviction and should consult with an attorney if possible. If you can't afford an attorney, try Legal Services; also see if there is a branch of the Community Health Law Project in your area.