I'm renting out a really nice apartment and I don't want it to become overcrowded or too noisy. Can I limit the number of tenants without getting into legal trouble?
You can set a limit to the number of people who can live in your rental—as long as you comply with all relevant housing laws.
State and local health and safety codes that set maximum limits on the number of tenants (based purely on the size of the unit and number of bedrooms and bathrooms) may support your limit on number of occupants. But you are not free to set unreasonably low figures (for example, two people for a two-bedroom flat) in order to maintain a quiet atmosphere or to reduce wear and tear.
Federal occupancy standards require landlords to allow two persons per bedroom—unless you can point to legitimate business reasons that justify a lower number (this is difficult to do). And state or local occupancy standards may allow even more people in the rental than the federal law does.
If your occupancy policy limits the number of tenants for any reason other than health, safety, and legitimate business needs, you risk charges of discrimination against families. Before setting an occupancy limit, contact your local and state housing authority for information, or the U.S. Department of Housing and Urban Development (HUD) for the specifics in your area. For contact information, check the "State Info" section on the HUD website.
For details on setting occupancy limits and advice on avoiding discrimination against families, see Every Landlord's Legal Guide or, (if your rental property is in California), The California Landlord's Law Book: Rights & Responsibilities.