This paper deals with how the major issues of public health in the United States played a multifaceted role in enacting the National Health Act of 1946, which was the first enactment of overarching mental health act at the federal level. At the beginning of WWII, the state of mental health system in American society was barely known. However, at the early stage of the war, their Selective Service System (SSS) with the psychiatric screening process based on the lessons of WWI and psychiatric knowledge during the time had failed to sort precisely out unfit soldiers. Luckily, most soldiers suffering from acute symptoms such as extreme anxiety, depression, regression, exhaustion, even numbness or deafness in a short period were able to return to their duty after a few-day convalescence. However, concerns about America’s public mental health problems skyrocketed during and right after the war. As a consequence, the consensus that needed a federal level measure inevitably established. By examining the text of the legislature and the hearings of the House of Representative and the Senate, this study looks into what were the focused problems and concerns in the process of enactment. Around the issue of a federal level of mental health policy, there had been overarching considerations of related fields, including academic, administrative, and even civilian. Looking into the details of each field’s consideration within the Congressional discussion, this paper aims at grasping how the concept of mental illness and disease changed and how the prominent actors of legislatures responded to the changing concept of mental illness. Through detailed examination of the related materials, this study presents the interconnection between the consequences of the great war and the will to maintain American society sane.