The following passage is from the FTC website, which is helpful:
http://www.ftc.gov/bcp/conline/pubs/credit/repair.htm
Each of the nationwide consumer reporting companies — Equifax, Experian, and TransUnion — is required to provide you with a free copy of your credit report, at your request, once every 12 months.
The three companies have set up a central website, a toll-free telephone number, and a mailing address through which you can order your free annual report. To order, click on annualcreditreport.com, call 1-877-322-8228, or complete the Annual Credit Report Request Form and mail it to: Annual Credit Report Request Service, P.O. Box 105281, Atlanta, GA 30348-5281. You can print the form from ftc.gov/credit. Do not contact the three nationwide consumer reporting companies individually. They are providing free annual credit reports only through annualcreditreport.com, 1-877-322-8228, and Annual Credit Report Request Service, P.O. Box 105281, Atlanta, GA 30348-5281. You may order your reports from each of the three nationwide consumer reporting companies at the same time, or you can order your report from each of the companies one at a time. For more information, see Your Access to Free Credit Reports at ftc.gov/credit.
Otherwise, a consumer reporting company may charge you up to $9.50 for another copy of your report within a 12-month period.