This final rule amends HUD's fair housing regulations to formalize standards for use in investigations and adjudications involving allegations of harassment on the basis of race, color, religion, national origin, sex, familial status, or disability. The rule specifies how HUD will evaluate complaints of quid pro quo ("this for that") harassment and hostile environment harassment under the Fair Housing Act. It will also provide for uniform treatment of Fair Housing Act claims raising allegations of quid pro quo and hostile environment harassment in judicial and administrative forums. This rule defines "quid pro quo" and "hostile environment harassment," as prohibited under the Fair Housing Act, and provides illustrations of discriminatory housing practices that constitute such harassment. In addition, this rule clarifies the operation of traditional principles of direct and vicarious liability in the Fair Housing Act context.