Since 9/11 put the nation on alert, there has been a growing demand for workers with national security clearance -- and the jobs aren't all defense-related.

A security clearance is actually required for any job where sensitive information needs to be protected. So it encompasses people in a spectrum of careers, from attorneys to information-technology managers to mechanical engineers.

But you can't go about getting a security check on your own, says Evan Lesser, founder and director of career website Employees have to be sponsored by a contractor or government entity and the investigation is conducted by one of several federal agencies, including the U.S. Office of Personnel Management.

So if you want a career in a field that requires security clearance, try to get in the door by applying for nonclearance jobs in companies you're interested in and then applying for cleared positions. You also can apply for jobs requiring confidential clearance, which is the lowest tier of the three main clearance levels -- which also include secret and top secret -- and work your way up.

Just getting cleared for the lowest level makes you more desirable to other companies and the government since employers would prefer to hire precleared workers who don't have to go through the lengthy clearance process from scratch. What's more, it gives you access to jobs that would normally be closed to the public and higher pay than equivalent noncleared jobs.

Getting security clearance can take as few as six months to as long as three years. A year is typical, says Mr. Lesser. "The higher you go, the more they will dig."

To make the process as smooth as possible, it's important to be prepared. Download clearance applications SF85 and SF86 from the Office of Personnel Management ( and use them as a guide. Don't omit anything that may raise red flags. And be prepared to explain why you have a drunk-driving conviction or a home foreclosure. No single, minor problem will sink you because most government agencies weigh many different factors.

Deal with any financial issues that suggest you're living beyond your means, including a lot of unsecured debt and credit-card charge-offs. Investigators consider financial instability to be a weakness that can be exploited by foreign powers.

Investigators also will delve into your travel history, criminal and driving records, credit score, Web presence and medical records -- typically to see if you have psychological issues like being bipolar -- says John Mardula, an attorney who handles security clearance cases at Marbury Law Group in Reston, Va.

Most important, be upfront. If the investigator finds something that wasn't included in the questionnaire, it can hurt your case and even lead to imprisonment.