A landlord is legally free to set whatever conditions he wants for a tenancy as long as they are reasonably related to his business needs and don't violate antidiscrimination laws. The Federal Fair Housing Acts (42 U.S. Code § § 3601-3619) prohibit discrimination on the basis of race, color, religion, national origin, gender, age, familial status (having children), and physical or mental disability (including alcoholism and past drug addiction). In addition, many states and cities also prohibit discrimination based on marital status, gender identity, and sexual orientation.
A landlord may reject you for poor credit history, income that a reasonable businessperson would deem insufficient to pay the rent, negative references from a previous landlord or employer, a criminal conviction, or a prior eviction lawsuit (even one that you won). As long as they don't discriminate, landlords can basically choose whomever they want. For example, a landlord can refuse to rent to smokers or disallow pets because smokers (and pet owners) as a group are not protected by antidiscrimination laws. If your landlord's policy is no pets, no smoking, or some other legitimate lease or rental agreement term, you're out of luck unless you can make some convincing arguments for your case. (Negotiating With the Landlord suggests ways to get around landlord restrictions.)
What about roommates? A landlord can limit the number of occupants for health and safety or legitimate business reasons. A landlord may not adopt a low occupancy standard if the result eliminates families with children—this is a violation of the fair housing laws, as discussed in Discrimination Prohibited by Federal Laws.
Caution! You are your own worst enemy if you lie on your rental application. Your landlord can easily find out that you don't make $50,000 per year by talking with your employer. Misrepresentations on the rental application are always legitimate grounds for rejection. And even if you slip by, ask yourself whether you want to rent from a landlord who is so careless. Would you be concerned to learn that the “former schoolteacher” next door is really a recently released rapist? If the landlord didn't check up on you, he probably didn't check up on your neighbor, either.
Most landlords will want you to fill out a rental application with information on your employment, income, credit and financial information, rental housing history, and any criminal convictions. It's legal to ask for all this information and use it to make rental decisions. Landlords may also legally ask you for your Social Security and driver's license numbers and (except in New York and California) for proof of your legal residency in the United States. Landlords may even ask if you smoke or if you've ever been sued.
How far can landlords go? They can ask for any information that will:
Questions that don't relate to these two issues are probably not legal. Keep in mind, however, that not all discrimination is illegal, so some questions that may not “sound right” may in fact be legal. (See “Are You Two, Like, Together?” below.)
Look at it this way: When you rent a car, you're often asked for multiple forms of ID and your driving history. Renting a place to live isn't all that different: The landlord, as much as the car rental agency, needs to know whether you're a good risk and how to find you if things go awry. In fact, since rental property is a much bigger investment than a car, a landlord is motivated to be even pickier.
While landlords are entitled to ask business-related questions on a rental application or during an interview, there is an important hitch: They should subject all applicants to the identical set of basic questions. As mentioned above, federal and state antidiscrimination laws make it illegal to single out members of certain groups (such as people of a certain race or ethnic background) for special treatment—and interview or application questions that aren't directed at everyone constitute special treatment. For example, landlords who ask about immigration history should ask all tenants, not just those whom they suspect might be in the country illegally. Questioning only those from the Mideast would amount to illegal discrimination on the basis of national origin. Similarly, requiring credit reports only from African Americans would also be considered illegal discrimination.
Do a little background investigation of your own. If your prospective landlord is conscientious, he'll probably take the time to learn about your rental and employment history. There's no reason why you, too, can't ask a few questions to find out whether you want to rent from him. Ask current tenants and neighbors what it's like to live there; ask the tenant whose unit you're considering why she's moving out. If you learn that she's leaving in disgust over poor management or dreadful neighbors whom the landlord won't evict, you'll want to think twice about signing a lease or rental agreement. Keep in mind that a building with a large turnover rate, and especially one where evictions are common, is probably not run very well.