This study fills a hole left in research about the Federal Bureau of Investigation. While previous authors have examined the Bureaus relationship to the executive branch, especially under its long-time Director, J. Edgar Hoover, comparatively little has been written about the Bureaus relationship with the United States Congress. Using their investigatory and appropriations powers, members of Congress could have maintained stringent oversight of Bureau officials activities. Instead, members of Congress either deferred to the executive branch, especially presidents and attorneys general, or developed close relationships with Bureau officials based on a shared politics, mainly anti-communism during the Cold War. Examining the relationship from 1907 through 1975 offers numerous examples of members of Congress looking beyond their oversight responsibilities. Even as Congress investigated Bureau actions, no meaningful legislation was passed limiting Bureau activities. Instead, members of Congress left it to the executive branch to correct problems. On issues like wiretapping, Bureau officials either misled Congress about the extent of their activities or ignored Congressional mandates in order to continue their anti-communist agenda. As the Cold War developed, certain Congressional committees began to use Bureau files confidentially in order to educate the public on the dangers of communism. While Bureau officials initially supported such liaison relationships, they were based on the source of the committees information never coming to light. Once that condition was violated, Bureau officials terminated the relationship, hampering the committees ability to use the communist issue to further political careers. To fully understand the FBIs role in 20th-century America, the relationship with Congress must be further explored. Focusing solely on Director Hoover or the executive branch is too narrow. Members of Congress had equal opportunity to oversee Bureau activities. That they did not fulfill this responsibility portrays the difficulty Americans have in containing the actions of investigatory agencies.