National Association of Realtors
http://www.realtor.org/

The NATIONAL ASSOCIATION OF REALTORS® , 'The Voice for Real Estate,' is America’s largest trade association, representing 1.2 million members, including NAR’s institutes, societies and councils, involved in all aspects of the residential and commercial real estate industries. Membership is composed of residential and commercial REALTORS®, who are brokers, salespeople, property managers, appraisers, counselors and others engaged in all aspects of the real estate industry. Members belong to one or more of some 1,600 local associations/boards and 54 state and territory associations of REALTORS®. They are pledged to a strict Code of Ethics and Standards of Practice.