First: Close any financial accounts — credit cards, bank or brokerage accounts — represented in your wallet, says Claudia Bourne Farrell, a spokesperson for the Federal Trade Commission. The longer you wait to report stolen credit or ATM cards, the more financial liability you will face if they are used fraudulently.

Then: Contact one of the three consumer-reporting agencies (Equifax, www.equifax.com; Experian, www.experian.com; and TransUnion, www.transunion.com) to have a fraud alert placed on your credit report. (Whichever agency you call is required to share the information with the others.) And ask your local department of motor vehicles or another government-ID–issuing agency to flag your file so that if anyone else tries to get a replacement license or ID in your name (after you have), the agency will know it is fraud. Finally — since even items that may seem unimportant, like a gym or work ID, can be used for identity theft — notify all the organizations you’re connected with and tell them you lost your cards.