Most landlords will look for any excuse these days to seize a rent-stabilized apartment, so they can deregulate and raise rents to market level. An often-overlooked aspect of most rent-regulated leases concerns others who may be staying in your apartment. In general, unless you are in public housing - and even if your lease says otherwise - New York law allows tenants to live with their entire immediate family, plus at least one roommate who is not related. If you have a guest that stays with you for more than a few days, your landlord may try to use this as grounds to evict you. Let's say you already have roommates, and one of your friends currently has no permanent living accommodations, so you let the person stay with you until he or she finds a place. Don't be surprised if you get legal papers from your landlord claiming you are violating your lease because of the extra people living with you. There are defenses in Housing Court to these kinds of proceedings, but you risk blacklisting. Defending yourself in New York State Supreme Court can avoid blacklisting, but can also be more expensive, and you may or may not be able to recover attorneys fees. If you think you could have a problem with your landlord based on your past experience, or that of neighbors, it might be best to explain to prospective guests that you can't jeopardize your lease, and help them find another place to stay.