“Withholding information from us will not work in your favor,” says Ronald S. Patrick, deputy director of talent development at the Central Intelligence Agency, which receives up to 150,000 résumés a year. Applicants who are offered a job go through a monthslong security clearance, including an intense background check. To pass, you can’t have been convicted of a felony (“That’s a showstopper for us”); also, no recent illegal drug use. You will be asked about drugs in the application. Tell the truth. “We don’t expect you to be shockingly, squeaky clean,” Patrick says. “We expect you to have lived a life, to have exercised bad judgment, to have gone through adolescence and made mistakes.”

Get your finances in order. “The No. 1 reason why Americans spy is for financial gain or need,” Patrick says. The C.I.A. sees bad credit and mountainous debt as potential liabilities. Prepare to be spied on. Investigators will come to your town; walk your streets; talk to your ex-colleagues, former roommates and nosy neighbors. They’re looking for people not listed as your character references, especially those who don’t like you. “I went through a lot of shoes,” Patrick says of his former role as a background investigator.

Keep your romantic interests American. “If you’re in love with a Russian citi­zen,” Patrick says, “we cannot take that risk.” Sign over your medical records. “Tell us everything,” Patrick says. “It may be embarrassing. It may be something you want to forget, something you’ve put in your past — tell us about it anyway.”

Be prepared to take a mandatory polygraph test, which Patrick describes as an “exceedingly reliable” way to find out whether you’ve been truthful. You will have many chances to disclose your secrets. Reveal them early and often. If investigators find out late in the process, through the polygraph interrogation or from sources, that you’re a regular stoner, say, or that your father is an arms smuggler, it will not reflect well on your trustworthiness. “This is the very last question we ask in the polygraph,” Patrick says. “ ‘Is there anything else that you want to tell us that we haven’t talked about?’ ”