The federal Fair Housing Act prohibits discrimination in all stages of the home buying process on the basis of race, color, national origin, religion, sex, familial status or disability. In particular, housing advertising that indicates a discriminatory preference based on one of these factors is illegal. The U.S. Department of Housing and Urban Development (HUD) has published guidelines for those who advertise homes for sale. You can report housing discrimination to HUD in a number of ways, including via phone at 1-800-669-7777 or via web form. HUD provides a number of resources for consumers and professionals relating to fair housing.
State and many local governments have similar laws prohibiting discrimination in housing. Find local fair housing enforcement agencies around the country using any search browser.