The global financial market turmoil that started in August 2007 has been followed by a severe economic downturn.Indeed,the U.S.economic recession is on track to be the longest and deepest of the postwar period.This Economic Letter describes the Federal Reserve’s monetary policy response to this financial and economic crisis.A key element of this response has been a reduction of the federal funds rate—the Fed’s usual monetary policy instrument—essentially to its lower bound of zero.Still,with the economy continuing to slump,additional stimulus appears warranted,and the Federal Open Market Committee (FOMC 2009) has promised to“employ all available tools to promote economic recovery and to preserve price stability.”Therefore,the Fed has eased financial conditions by employing a variety of unconventional monetary policy tools that alter the size and composition of its balance sheet.It has also communicated more explicitly its expectations for the course of monetary policy and the economy in order to help guide households and businesses during these uncertain times.