Building a credit history - key to financial freedom for women.

Less than 10 years ago, divorced women were commonly denied credit, single women had difficulty getting loans, and newly married women often had to reapply for charge accounts based on their husbands' credit ratings - regardless of their own income and former bill-paying record.

Since the passage of the Equal Credit Opportunity Act in 1975, these types of inequities have largely disappeared. But not all women are taking full advantage of the rights they've gained.

''It seems women still have problems obtaining credit - it's not so much overt discrimination as it is an absence of a credit history,'' says Meredith Fernstrom, vice-president of the American Express Company.

For single women just entering the job market and married women who only use bank and charge accounts in their husbands' names, ''The important thing to realize is, you can't go out and gain credit automatically without building your own financial accounts first,'' Ms. Fernstrom says. ''Any creditor is going to look at a person's credit history who is applying for a new form of credit.''

Today, she notes, a credit reference is used for more than just obtaining a loan or a charge card. In California, for example, some apartment house owners get a person's credit reference before they will rent an apartment. Some insurance companies run a credit check on prospective clients, and some employers also look at a person's credit rating before hiring him. A good credit history is also necessary to get a loan to start your own business.

''Your credit rating becomes a measure of your integrity and responsibility, '' says Ms. Fernstrom. ''That's one of the main reasons it's important to maintain a credit rating in good standing.''

The first step in establishing a credit history is to open a savings and a checking account at a local bank. A married woman may still want to retain some joint accounts with her husband, but she should establish at least a savings account in her own name, Ms. Fernstrom advises.

''Some men feel a little threatened by wives having separate accounts, but it's really for the protection of both,'' she says. ''If a woman is widowed or divorced, or in case of accident, it's easier for her to carry on everyday financial transactions if she has her own former credit.''

Ms. Fernstrom says one of the easiest forms of credit to get is a department store charge account, particularly if you are a regular customer and know the management. Next, a person might apply for a bank card such as MasterCard or Visa.

If a woman shares joint accounts with her husband, she should check the credit bureau to make sure she is on file and that shared accounts are registered in her file as well as her husband's. Divorced women can apply for new credit on the basis of accounts formerly shared with their husbands.

A married woman who uses charge accounts in her husband's name as an ''authorized user'' may not realize she can also develop a credit history, says Marlene Zigman, associate director of the Consumer Credit Project Inc., a nonprofit organization in Barrington, Ill., which offers a free counseling service. In this case, creditors will report information in both names at the request of either spouse.

According to Ms. Zigman, another issue that often arises is: ''I'm getting married and don't want to lose my credit history.''

If a woman marries and changes her name, Ms. Zigman explains, credit bureaus are not required by law to cross-reference the credit history under her maiden name to the new file under her married name. If the woman makes a specific request, some bureaus will transfer the previous credit history to the new file for a fee. If the bureau does not offer this service, the woman has to start building a new credit history under her married name.

In addition, your credit history does not necessarily move with you if you move to another part of the country. You may need to make a special request to transfer your file to a new credit bureau.

There are about 2,000 credit reporting bureaus across the country. Most are linked to one of five major companies that maintain enormous computerized files. To find your local credit bureau, check the Yellow Pages under ''Credit Reporting Agencies.''

Under federal law, you have a right to know what is in your credit file. But unless you have been denied credit within the last 30 days, you will probably be required to pay a $5 to $10 fee to get a copy of your file. Before releasing the information, a credit bureau may send a form for you to sign or use some other protective procedure.

''If there is incorrect information in your file, there is a legal remedy,'' Ms. Zigman says. If requested, the credit bureau is required to investigate the questionable item and the information must be dropped from the file if its accuracy cannot be verified. If the item is correct, you can attach a letter explaining your side of the issue.

''New Credit Rights for Women,'' a publication explaining women's credit rights and how to establish a credit history, is available for $2, plus $1.50 postage and handling. Send checks to the Consumer Credit Project Inc., 261 Kimberly Road, Barrington, Ill. 60010.m