The Multiple Listing Service, also called MLS, allows subscribers to search homes for sale. Typically used by real estate agents and appraisers, the MLS offers a consolidated listing of most homes on the market. Besides access to home listings, MLS offers members market analyses, tax information and property history. Each state has its own MLS. Sometimes, regional MLS groups form. Member Realtors can also receive keys to lockboxes, used on houses for sale to increase access.

Join your local board of realtors. The local boards are subgroups of the National Association of Realtors, which lobbies, educates and conducts research for the industry. Some state's realtor associations allow non-licensees to join for the sake of subscribing to MLS. Usually, realtor association members have their real estate, broker's or appraisal licenses.

Compile necessary documents. For licensed real estate agents, brokers or appraisers who join an office already in the MLS network, gather your license and fill out the application. Non-licensed applicants should simply fill out the form. Often, either the office manager or principal—the person under whom licensees operate—must sign the application form.

Pay the fee, which varies by state. How MLS levies the fee also varies. In Arizona, for instance, members pay annually, while the MLS for New England charges monthly.

Submit your application. In some states, prospective members apply directly through the Realtor Association. In other states, the MLS group takes applications.