The period of McCarthyism is also referred to as the Second Red Scare . It happened at the same times as increased fears of Communist influence on American institutions , espionage by Soviet agents such as the Rosenbergs , heightened tension from Soviet control over Eastern Europe , the success of the Chinese Communist revolution ( 1949 ) and the Korean War ( 1950-1953 ) . The term has its origins in the period in the United States known as the Second Red Scare , lasting roughly from the late 1940s to the late 1950s and characterized by heightened fears of communist influence on American institutions and espionage by Soviet agents .