Ruth JudsonThe incidence of currency counterfeiting and the possible total stock of counterfeits in circulation are popular topics of speculation and discussion in the press and are of substantial practical interest to the Federal Reserve, the U.S. Treasury and the United States Secret Service (USSS), who are jointly responsible for U.S. banknote design, including security features, and production. This paper assembles data from Federal Reserve and USSS sources and presents a range of estimates for the number of counterfeits in circulation in the United States. In addition, the paper presents figures on counterfeit passing activity by denomination, location, and counterfeit type.