This chapter looks at how new forms of digital money – in particular stablecoins, digital banknotes (retail central bank digital currencies or CBDC), and crypto currencies (Bitcoin) – impact the ability of the central bank to effectively implement monetary policy. This chapter first illustrates how central banks typically steer market interest rates to the desired level. It then shows how these new forms of money change the balance sheets of the central bank, commercial banks, and households and firms. We find that impact of stablecoins, retail CBDC, and cryptocurrencies on the effectiveness of monetary policy appears to be modest. Since retail CBDC will reduce the deposits at commercial banks, the central bank may have to increase its lending to them to keep the credit provision to the economy at the previous level.