The Federal Bureau of Investigation (FBI, the Bureau) is the lead federal law enforcement agency charged with counterterrorism investigations. Since the September 11, 2001 (9/11) attacks, the FBI has implemented a series of reforms intended to transform itself from a largely reactive law enforcement agency focused on investigations of criminal activity into a more proactive, agile, flexible, and intelligence-driven agency that can prevent acts of terrorism.This report provides background information on key elements of the FBI terrorism investigative process based on publicly available information. It discussesseveral enhanced investigative tools, authorities, and capabilities provided to the FBI through post-9/11 legislation, such as the USA PATRIOT Act of 2001; the 2008 revision to the Attorney General's Guidelines for Domestic FBI Operations (Mukasey Guidelines); and the expansion of Joint Terrorism Task Forces (JTTF) throughout the country;intelligence reform within the FBI and concerns about the progress of those reform initiatives;the FBI's proactive, intelligence-driven posture in its terrorism investigations using preventative policing techniques such as the "Al Capone" approach and the use of agent provocateurs; andthe implications for privacy and civil liberties inherent in the use of preventative policing techniques to combat terrorism.This report sets forth possible considerations for Congress as it executes its oversight role. These issues include the extent to which intelligence has been integrated into FBI operations to support its counterterrorism mission and the progress the Bureau has made on its intelligence reform initiatives.