The United States established the Intelligence Reform and Terrorism Prevention Act (IRTPA) of 2004 with the fundamental concept of improving information sharing within the Intelligence Community to boost its counterterrorism efforts in Homeland Security. The IRTPA of 2004 was established to enhance the communication channels among intelligence agencies, facilitate data exchange and analytic tradecraft etc. to reduce intelligence failures that could result to catastrophic terrorist attacks like the September 9, 2001 terrorist attacks. Unfortunately, more than a decade after the establishment of the Act, there are doubts on the level of National Security threats after 2004 coupled with arguments on the effectiveness of the IRTPA of 2004 on U.S. counterterrorism efforts. Therefore, this research paper evaluates the impact of IRTPA of 2004 on homeland security focusing on the degree of terrorist activities from 1990 – 2018. Comparing the level of terrorist incidents between 1990 – 2004 (before the Act) and 2005 – 2018 respectively, to accept or reject the null hypotheses that the IRTPA of 2004 decreases threats to National Security.