A credit security freeze denies access to your credit file. I first learned about it last summer from Brian Krebs, but didn’t implement it until a couple months later. It took me about 45 minutes and $20 to activate the freeze with the five major credit bureaus. This goes a long way to reducing the threat of identify theft, with very little energy expenditure required. A proactive defense is superior to reactive monitoring services. If you need your credit pulled monthly or more frequently, constantly freezing and unfreezing your file would probably be an annoying inconvenience. For the rest of us, I’m not sure if there is any good reason not to enable the freeze.