www.realtor.org/
The National Association of Realtors is the world's largest professional association with over 1.3 million members. It is composed of Realtors who are involved in residential and commercial real estate.
http://www.irem.org/
IREM is a professional real estate management association serving both the multi-family and commercial real estate sectors.
http://www.narpm.org/
The National Association of Residential Property Managers is an association of real estate professionals managing single-family and small residential properties.
