You'll typically pay $30, maybe less if you've been a victim of ID theft, to freeze your report at the three major credit bureaus - Equifax, Experian and TransUnion. That's much less than the $120 a year you could spend for a (less effective) credit monitoring service.
On the other hand, the freeze prevents even you from getting new credit. So before you start, say, car or home shopping, you'll have to pay up to $10 per bureau to temporarily thaw your report.
If you apply for credit frequently and you haven't been an ID theft target, instead of a freeze try this: Check your credit status for free by ordering your report every four months from one of the credit bureaus at annualcreditreport.com.
And call one of the bureaus to request a 90-day fraud alert be placed on your file at all three agencies. This notice will alert lenders to take extra precautions before granting credit in your name. You must request the alert every three months, but it won't cost you a dime.
The prudent conclusion: A freeze is fine, but getting copies of your report and adding a fraud alert can often do the job.
Last updated January 17 2008: 5:45 PM ET